Since I can remember, I’ve used paper to develop drafts of 3D cosplay elements that I’ve made.
Because paper is cheaper than foam, you can make mistakes, figure out the exact shape you want for parts, and determine exactly how much foam to buy.
These are all huge plusses.
I use a combination of poster board (like the one you can get in 10 packs from office supply shops), scrapbook cardstock, and masking tape.
Building the Shape
Beginning with shapes roughly cut to the size I want them, I cut and start attaching pieces together. The process is as much trial and error as it is being precise.
I might know, for instance, that a round pauldron is 7 inches from end to end and that the shape I’m creating is going to be a curve that’s much longer than 7 inches. Consequently, I might start with two large triangles that are 12 inches across.
I’ll tape the base and play around with how the paper fits/looks until I come up with a shape I like. At this point, I can use tape to secure the shape and scissors to cut off any excess.
Taking care to shape pieces incrementally, eventually I get to a point when the shape of the taped form is just what I want.
If ever I cut too much off of a piece, it’s easy enough to simply tape a piece of paper on (to extend a sheet) for small mistakes or start over with a large sheet for bigger pieces.
Poster board is particularly easy to work with because it is rigid enough, easy to cut, simple to repurpose, and traces easily.
Taking it Apart
Speaking of tracing, when I’m finished with all of my forms, I simply using a large marker to draw cut lines such that when pieces are cut, they lay completely flat. Along all of these cut lines, I’ll draw darts so that I know what edge connects to what. I review the shapes a couple of times before marking, taking into consideration things like the overall size and thickness of my foam.
Reviewing the form before marking, I am able to make adjustments before actually cutting along these lines. I also use this time to make sure that when I cut along the lines, pieces of paper do not fall apart. I’ll tape all of these loose parts at this point to make sure that templates stay intact.
Transferring to Foam
With my paper template pieces cut, I’ll then lay them on the foam. Once I’m happy with the placement of every piece, I’ll use a marker to trace the outline of the shape onto the foam.
Sometimes, I’ll just template one side of something. For shapes that should be mirrored, I’ll mark the paper templates with front side or back side to not only keep track of the placement of the cut foam piece but make sure that I’m mirroring appropriately. I’ll make a similar mark on the foam, where it won’t be seen on the finished product to make sure that pieces fit together appropriately.
Pro Tip: A lot of this will be trial and error, but a consideration to make is the thicker the foam, the more of a border you’re going to want to add around each cut piece. This border is out of consideration that, if you cut a piece of thick foam to the same size of your paper, your finished form is going to be more snug.
A more snug fit may be okay, but for foam pieces like a helmet, where tolerances really matter, not adding padding can mean having to go back to the cutting board.
A rule of thumb I go by is to add padding around the templated paper piece equal to, at least, the thickness of the foam.
As you hopefully can tell, paper can be really useful in the creation of templates and cutting foam pieces. Start with paper and you’ll save a lot of time and money building that awesome cosplay of yours.