I've been cosplaying Harley Quinn for about five years now and everyone is always astonished by how I explain the making process. This only took me about 2 days non-stop to finish but I highly don't recommend doing that as I have an insomnia medical condition that allowed me to finish in less than 24hrs straight.
Step 1: Buying 2 Body Suits and Cutting Them
These can be from either a Halloween store or even online. I personally bought mine online for around $50 at Milanoo.com, they arrive rather quickly. The first thing you'll want to do is wash them in cold water BY THEM SELVES. This prevents color leakage to each other and when you go to wash it after a convention. Tumble or air dry is preferred but you can dry them on hotter settings. Just consult the website if you're still unsure. After you have them washed put them on inside out and zip them up. You may need a friend to help you out but I did this by myself so it is possible. Mark under your bust along the entire costume in a rather straight line and then make another straight line from the middle of your collar bones down to the middle of your crotch. Do this step on both suits, and then cut along those lines making sure not to cut anything else. You can also cut off any hoods or zippers as well as the gloves. When cutting off the gloves make sure the one you will be keeping is long enough to tuck under your wrist cuffs and the one you wont be keeping can be cut off as close t the thumb as you can. Then Pin together the sections you will be keeping.
Step 2: Sewing Everything Together
Now, I don't have a picture of me actually sewing the suit together but I'll walk you though it. Most people will recommend using a zigzag stitch on a conventional sewing machine but if you have a surger, it's better to use that in the long hall. I personally use a regular straight stitch, now I know what you're thinking, "How do you keep it from breaking?" I sew once, do a stretch test, then sew multiple times over any seams that may have popped. Usually mine is fine the first time around. So after you figure out what your using and how you're using it, go ahead and sew the sections you decided to keep, together. This takes a very long time depending on how fast of a sewer you are. Everyone takes a different amount of time depending on their comfort and skill level. After it's all sewn together you need to put a zipper in the back. I use an invisible zipper that's 22" long in either red, black, or white. You can find tutorials for how to insert those at your local craft store or online.
Step 3: You're Almost Done
After you've successfully installed a zipper and given it a stretch test, you're ready to lay on the diamonds. Normally people will tell you to top-stitch them (Which is recommended) but that's not how I put them on. I use Peel and Stick sheets that you can find in the craft isle at Walmart or at your local fabric and craft store. Just ask around for help if you need it. My diamond sizes are as follows; Large: 4X3, Medium: 3X2.5, Small: 2.5X1.5. You can always change the dimensions to whatever you like, these are just my preferred sizes. After you have them all cut out and ready to stick on, you need to trace the outlines for all of them onto the Peel and Stick sheets, cutting them out and then removing one side of the backing and placing one diamond on top with the back side down. After all of your diamonds have been backed, you can remove the other backing one at a time and placing them on your body suit while it is on you (You may need a friend here again) There are also other alternatives like iron on patches.
Step 4: Congratulations! You Now Have a Finished Harley Quinn BodySuit
Now you can show it off to the world. Don't forget to check out my social media and give my Etsy shop a look at.
Remember to have fun and be nice!
Youtube: The Cupid of Crime