How To Alter An Existing Bodysuit Pattern

Do you need to make a crazy looking bodysuit for your next cosplay, but don’t know where to start?  Its actually quite easy to use a simple bodysuit pattern you can buy in store and alter it to fit your needs!  In my example, I use Zero Suit Samus’s bodysuit as it appears in Super Smash Bros Wii U, but this method will work for any character with any kind of bodysuit, no matter how complex.

PLEASE NOTE:  I do not go into depth on how to sew in this tutorial, so you will need some basic sewing knowledge before diving in.  If you need more information on sewing techniques, there are tons of tutorials out there to learn from!  All you have to do is search!

Material List:

  • Pre-existing bodysuit pattern
  • 4 way stretch mock up fabric (Something cheap, color matters not. Best if it has the same stretch as your costume fabric)
  • 4 way stretch fabric for the final costume (use stretch knit, spandex, stretch vinyl, etc, in all the colors you need)
  • Thread in color(s) of bodysuit
  • Fabric Scissors
  • Normal Scissors
  • Measuring Tape
  • Chalk or Pastel Pencil in different colors
  • Pins
  • Sewing Machine
  • Appropriate Needles
  • Paper
  • Pencils
  • Ruler/Other measuring tools
  • Zipper

Step 1: Cut out your pre-existing pattern pieces

To start off, you’ll need to create a mock up for your bodysuit, and to do that, the way that works best for me is to make one from an existing pattern.  There are many you can find, but my personal favorite to use is the Yaya Han pattern from Cosplay by McCalls. This pattern is not best for everyone though, so if you’d prefer something a bit easier and with fewer panels, you might want to consider a different pattern.  For this tutorial, I’ll be using Yaya Han’s pattern, but know that this method will work just as well with any pattern.  Be sure to get a pattern in your size!  You can find the range of sizes on the package.  Just look up your measurements on the chart provided on the back of the package and match yourself with the correct size



Before you cut anything, measure yourself!  You’ll need to make sure you’re cutting out the right pieces for your size.  If some of your measurements match one size, while other measurements match another, go with the larger size.  You can always take the bodysuit in at the areas it’s too large later, but its much harder (and sometimes impossible) to make it larger in areas that are too small.  Once you know for sure what size you want to use, cut out all the corresponding pieces of the pattern.

Step 2: Make a mock up of your bodysuit

The next step is to make a mock up of your bodysuit pattern.  Not only is this EXTREMELY necessary  in order to make your crazy looking bodysuit later, but this will also give you the opportunity to alter the fit before cutting into your costume fabric. It is VERY unlikely that any pre-existing pattern you buy will fit you perfectly unaltered.  Everyone’s body is different, and its impossible for a pattern company to make a pattern that will automatically fit everyone.  You should expect to have to alter the pattern slightly. However, even if it doesn’t fit you perfectly, its a great place to start and it is oftentimes easier to alter an existing pattern than it is to make one from scratch, especially when it comes to something like a bodysuit.


To make your mock up, you’ll simply need to cut out all the pieces of your pattern from your cheaper mock up fabric and sew them together correctly.  It’s important that your mock up fabric has the same kind of stretch that your costume fabric does.  If it doesn’t, your mock up might end up fitting, but your final costume might not.  Better to be safe!



On your pattern pieces, you’ll see areas on the patterns that have circles, dots, and triangles.  Clip into the triangles, and mark any circles and dots with a piece of chalk or pastel pencil.


I personally like pastel pencils better because I can sharpen the easily and that makes it easier for me to draw on the fabric with them. It takes time to do this, but it will help greatly!



Now, instead of following the sewing directions exactly to assemble your bodysuit mock up, all you have to do is sew each panel together with a basting stitch.  You should still follow the order the pattern directions tell you, but you don’t have to worry about using a stretch stitch, pressing, seams, or anything else the pattern tells you to do.  This is not only faster, but its very easy to take out basting stitching if you need to, whereas a zig zag stitch or straight stretch stitch would be very difficult.  Basting is your friend! Simply pin your corresponding pieces in place and baste!



You also do not need to worry about hemming the edges here.  All that matters is that you can put the bodysuit on without it falling apart at the seams.  Do put the zipper in though, as you’ll need to be able to close it to alter it in the next step.


Instead of using a basting stitch to install the zipper, I used a long straight stitch.  I did this to make sure the  zipper didn’t pull loose when I put it on, but would still be fairly easy to take out when I was ready to take it out.

Side note: If you’re using Yaya Han’s pattern like I am, it will say on all the package that it is for 2 way stretch or 4 way stretch fabric.  I like using a 4 way better than a 2 way because 4 way stretch is easier to fit  (for me) because I don’t have to worry about an area not being able to stretch around my body, and I also don’t have to worry as much about how I place my patterns on my fabric to cut out, because it stretches no matter what.  If you use a two way stretch, you’ll absolutely have to make sure all your pieces are going to stretch in the right direction

Step 3: Start Altering

Time to put your mock up on!  Its better to put it on inside out at this point, so be sure to do it and make your life easier!

I have it right side out here, but really you should put in on inside out

Take a look at how fits, and notice all the areas that need adjusting.  I had to take mine in at the sides of my waist, so I pinched the fabric in as tight as I wanted it to be at those seam lines, and pinned it in place. I also needed to take it in slightly around the armpit, so I pinched those seams in and pinned them in place to fit as well.  Now take it off, and sew in the new seam lines with another basting stitch.  Put it on again to see the new fit.  If you’re happy with it, Great!  If not, readjust the pins so that the suit fits better and try again.  Keep working at it until you’re happy with it.  To make things easier on yourself later, also cut the seam allowance  to match the rest of the bodysuit on the areas you altered.  So if your pattern originally had a 5/8 inch seam allowance, cut all the seams you took in to also have a 5/8 inch seam allowance.

Step 4: Draw the crazy bodysuit design onto your mock up

This next step can be somewhat tricky to do on your own, especially if you need to draw onto the back of the bodysuit, so its a good idea to have a friend to help you out if possible.  Once you’re happy with the fit of your bodysuit, it is time to start marking where all the new lines for the details and new seams will need to be on your final bodysuit.  In this tutorial, I am using Zero Suit Samus’s bodysuit from Super Smash Bros Wii U for my example.  Samus’s bodysuit has two different colors, (light blue and dark blue) and some pretty crazy seam lines.  So, while wearing the mock up bodysuit, I grabbed a pastel pencil and started drawing all over the suit wherever I needed new lines for the different colored sections.


Once I was happy with the placement of all these new lines I just drew, I grabbed another pastel pencil in a different color and drew over them to finalize their placement.



Step 5: Disassemble

Its now time to disassemble your bodysuit. First things first, you need to take the zipper out so you can use it again later.  Just take a seam ripper and take the stitching out.



After that, its time to start cutting.  Once you start cutting, there is no turning back, so make absolutely sure you’re happy with all the new lines before you start cutting.  At this time, you also need to decide which of the original seam lines of the bodysuit you want to keep, and which you want to eliminate.


Zero Suit Samus’s Bodysuit has enough different sections to it that I really didn’t need to keep the majority of the old seam lines if I hadn’t wanted to, but I liked the aesthetic of some of the seam lines, so I kept a few of them even though I didn’t need to.  For example, I could have eliminated the seam lines that run horizontally in the front and made the bodysuit super smooth.  I happened to like the way that they looked so I kept them in.  Another thing you’ll need to think about when cutting apart the bodysuit and making sections out of it is how your body is shaped and how you want the suit to fit.  I have a pretty curvy body (fairly large bust and hips, small waist), so keeping some extra seam lines around the torso allowed me to shape the bodysuit to fit my frame better.  I did however, eliminate the original seam lines between the legs and the torso, since with my new sections around the legs I no longer needed them.  Unless you’re making Zero Suit Samus’s bodysuit as well, you won’t be able to do exactly what I’ve done.  You’ll need to consider all these things and make a decision on what to will work best for your project.

When you do cut apart your bodysuit, make sure to cut along your finalized lines and mark each one so that you can see exactly how they’re supposed to fit together again.  I usually use letters to do this.  You don’t want to cut it all apart only to realize you don’t remember how it goes back together!  Also be sure to mark each piece according to what color/fabric it will need to be later.


On areas you are keeping the original seam lines, you can simply take the stitching out rather than cutting it apart.

Also be sure to keep in mind what areas have seam allowances already and which areas do not.  Any thing you’ve cut along your own lines will not have a seam allowance on it, so you’ll have to add the seam allowance later.  The ends of the legs and arms, however, will already have a seam allowance built in, since those came from the original pattern.  If you kept original seam lines by taking the stitching out rather than cutting, those areas will also already have the seam allowance.  It might be confusing to keep track of, so its a good idea to mark areas you’ll need to add a seam allowance so you don’t forget.

Remember: Unless your bodysuit is asymmetrical, you only need to draw on and cut out ONE HALF of your mock up.  Do not waist your time drawing the entire thing out and cutting the entire thing out when you only need to do half.  

If your bodysuit is asymmetrical (for example, Cia from Hyrule Warriors) you WILL need to draw out and cut out both sides.

Step 6: Transfer your new pattern pieces to paper and cut those out too

Now that you have all your bodysuit sections cut out, you’ll need to transfer the new pattern pieces to paper. So take each new pattern piece that you cut from your mock up and place it on the paper, as flat as you can get it, and trace around the piece onto the paper, being sure to add in the seam allowance where needed.  Keep very close attention to all the areas that need seam allowances added and those that do not.  If you forget to add a seam allowance to a section, your pieces WILL NOT fit back together correctly.  The same goes for if you accidentally add a seam allowance where you did not need to add one.  So be extra careful and double check everything before you commit.


Also take the time to label each piece according to what it is, and transfer all the letters and markings so you can keep track of each piece and where it goes.


Add the same seam allowance your original pattern used.  Patterns almost always use a 5/8th inch seam allowance unless otherwise stated in the directions, but it wouldn’t hurt to check your pattern to make sure thats what it is.  Just take a ruler, or whatever measuring tool you’re using, and mark the seam allowance along all the edges you need to add it.


Also, take the time to actually draw the lines for the seam allowances onto each each piece of paper.  It is tedious, but it will make your life a lot easier later on.


Once thats all done, cut them all out!



Step 7: Cut out your Costume fabric

Now, separate each pattern piece according to what color and/or type of fabric it needs to be, and cut the fabric for each piece accordingly.  Since you’re working with stretch fabric, check it to see if the stretch is the same going both ways, or if one way stretches more than the other.  If the stretch is the same both ways, then you don’t need to worry about anything at all.  My fabric was 4 way stretch, but it felt to me like one way was slightly more stretchy than the other, so I made sure when I placed my pattern pieces over the fabric, that I had them all facing the same way so that the stretch would face the same way throughout the suit.  If you’re using a two way stretch, you’ll obviously need to make sure all the pieces are facing the right way or it might not stretch around your body when you go to wear it.


I HIGHLY recommend just using a 4 way stretch fabric.  If you use 4 way stretch you don’t have to worry about which way your pattern pieces face, so it makes the entire process a lot easier.

Anyway, once you have all of that figured out, go ahead and pin your pattern pieces down to your fabric. If you’re using a vinyl or any type of rubbery coated fabric for that matter, you will want to refrain from pinning the fabric anywhere that is going to be visible on the bodysuit.  With vinyl fabrics, anywhere you poke a hole, the hole will stay forever. Some people prefer to not use pins on vinyl fabrics at all because of this, but as long as you keep the pin inside the seam allowance, it doesn’t matter.  If you’re concerned about using pins on vinyl, you can also tape the pieces down with scotch tape.  If you’re using a regular spandex though, pins won’t damage your fabric at all, so in that case, pin wherever you want!  Now grab a pair of sharp scissors and cut all your pieces out!


If your bodysuit is symmetrical, you only needed to cut out half of the mockup, which means you only have pieces for one half of the bodysuit.  In this case, just fold your fabric in half before pinning your pattern pieces down to your fabric.  This will allow you to cut both the left and right side of the bodysuit at once.  If your bodysuit happens to be asymmetrical, you obviously will need to cut each piece separately.  Basically, if you need a right and left side, make sure you’re cutting two pieces from folded fabric.  If you only need a piece cut for one side, be sure to only cut that one piece.

Step 8:  Prepare to Sew

Its almost time to start sewing, but not quite yet!  First, off, you’ll make your entire sewing process a lot easier if you do one simple thing.  Poke holes into each corner of your pattern piece where he seam allowance lines meet and use those holes to draw dots onto your fabric wherever they line up.


Remember the circles and dots from the original pattern?  Those circles and dots tell you where your pieces should line up with each other.  By poking holes where the seam allowances meet, you are essentially creating the same kind of dots on your new pattern pieces that already existed on the original pieces.  This will make lining all your pieces up properly a million times easier, because you can just line up the dots and you’re golden!  you won’t have to guess if you’re doing it right because if the dots lines up, its right and it they don’t, its wrong.  No guess work!  It will take a lot of time to do, but the ease it will give you later is worth every second.  Do this with every piece and transfer the dots onto both the front and back of each piece.  This will especially help if you have to sew inset seams.  Zero Suit Samus’s bodysuit has inset seams galore, so I doubt I would have even been able to complete the suit without those reference dots.

Step 9: Start Sewing!

After all that, you’re finally able to start sewing your actual bodysuit together!  Depending on the complexity of your bodysuit’s design, it could be very simple or very difficult.  Mine involved a lot of inset seams, so it was fairly difficult to do, and I had to take out the stitching and redo a few sections here and there to make it the quality I wanted, so if you have a hard time, don’t get discouraged!  Just power through and do your best!


When sewing a bodysuit, or any stretchy garment for that matter, you need to make sure you use some kind of stretch stitch.  A zig zag stitch is a good option, but I personally like to use a straight stretch stitch. Which you use is up to you.  Use whichever you’re more comfortable with.   Make sure you’re using a needle suited for the type of fabric you’re using and go for it!  If you took the time transfer all your dots before, which you should have, it will be super easy to match up the edges for all your pieces and keep them in the right place!  Just match the dots, pin in place, and line the edges up before you sew!  If you’re working with a curved edge, you may need to clip into the curve in order to make the fabric stretch around it.  To clip, just take a pair of scissors and cut into the fabric from the edge, but DO NOT go over the seam allowance!  If you’re working with inset seams, you’ll need to cut the outer corners and clip into the inner corners in order to sew the seam around them.

If you can, try to put the pieces together in the same order the original pattern required, but depending on how much you changed the bodysuit, that might be very hard or even impossible.  Mine didn’t look much like the original pattern at all, so I started with the torso sections first, and then moved onto the leg sections.  I also saved the side seams until after I had the front and back sections put together.  I sewed the inner leg seam together after that, then the collar, and of course, the sleeves after that.  At the very end, install the zipper into your bodysuit. Once it is all together, put it on and make sure it still fits right.  With all the different sections in your new suit, the fit might have been changed a bit, so if you need to take it in anywhere, take the time to do it now.  Mine ended up needing to be taken in at the sides a small amount again.  Last, all you need to do is hem the sleeves and legs and you’re done.  Now you’ve got a shiny, new bodysuit for your costume!


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