Intro: Make a Sewable Pattern of Any 3D Shape.
In this instructable I'm going to show you how to create fabric patterns of 3d shapes using uphostery foam. This method is great for making plush toys, puppets, furniture, props, costumes, etc... One advantage of using this method is that you can easily make patterns for more complex 3D shapes. For this example, I'll be making my favorite animal, the manta ray.
-Your fabric of choice
-An electric turkey carving knife (preferred)
Step 1: Trace Your Shape
I like to give myself a template before cutting into the foam by drawing shapes for the front, side, and top of the foam. This was fairly easy considering that manta rays are pretty flat and don't have limbs. For more complex shapes, it's sometimes a good idea to break it into separate parts like limbs or tails and pin or glue them together later on. If your shape is symmetrical, draw a line down the middle and save yourself some time in the next steps. If you're using sheets of foam or don't have a big enough block, I recommend using contact cement to join multiple pieces together. You can also do this to fix any mistakes made during the sculpting phase.
Step 2: Sculpt Your Foam
For this step I recommend using an electric turkey carving knife for the easiest and cleanest cuts. In the case that you don't have one, scissors will also work if you're desperate. It's okay if the surface is rough and ugly, because we'll later be covering it in fabric or discarding the foam completely depending on what you're using the pattern for. I start out by removing the corners and biggest un-needed pieces of foam first, and then refine until I have the shape I want. For this project I also used scissors to cut a mouth for my manta ray so I can later hide electronics inside.
Step 3: Pinning and Trimming
For this step, I like to start with my line of symmetry, or with the largest part of the foam sculpt that can be covered without any pinching or folding. If your sculpt is symmetrical, you'll only need to cover and pin one side. You can then just mirror your pattern later on. Make sure you're using a fabric that behaves similarly to your final fabric as far as stretching goes. Use pins to secure the fabric to the foam while pushing wrinkles to the edges. On curved surfaces where the fabric has to fold or wrinkle on itself, pinch the fabric into as few folds as possible and pin them down so they stick out. when you've covered and pinned the entire sculpt, cut these folds close to the foam. These will become seams that will shape your fabric.
Step 4: Tracing Your Pattern
When the foam is completely covered and completely smooth, with all wrinkles and folds removed, you can begin unpinning your fabric. Label and trace the remaining fabric and add a 1/4" or so outline to your seams and you're ready to make as many plush manta ray babies as your heart desires!
Step 5: Finished :^)
Here's what the toy looks like with the finished pattern (as well as some optional sewn gills, tail, and button eyes).