Weel , if you whould search for kigurumi masks you'll find that it's one of the most expencieve part of cosplay. And there is a reason. Cause them are made to last as long as the owner lives. Or longer. For the last two decades since kigs striked to consumer market from moovie and event supply markets there was a lot of innovations. And here is how I make them now.
Each mask firstly sculpted - by hand or digitally. Really hand sculpting is still nesessary even if I can print the form. Than I print the mold (It's as big as motor helmet and takes certain time and materials) and cast the mask in fiber reinforced resin. About 700 gr per mask.
And than the fun begins.
Cosplay crafting is all about surface. How many times you cared if an armor you saw at a convent or on the net made of cardbord, resin or foam? And how many times you cared about how it looks like steel, leather, alien material travelled through doxens of battles? So you can not show the mask if it hasn't been sanded properly and covered with layers of paint and clearcoats. I'm proud that my surface is smoothed and have 0.5 to 1 mm thick, satin-feel clearcoat. Having such a layer it's just natural to provide durable and strong undersurface.
I've learned it on a mistake. One day, 10 years ago, I've made a space creature costume made of duckt tape. And used a garden coating fabric as an undrlayer. That fabric adsorbes water. And sweat too. While sweat dissolves latex glue that used in duckt tape. So after several photosessions and convents my suit degrades into a cool-looking waste.
So that's how it's made. And it worth being made that way. You know, recently I got a letter from my customer who commissionned two WinX-inspired masks from me two years ago for using in event business. The question was how to saturate makeup after all that work. I'm proud that it was the only issue even after knowing there was only one layer of clearcoat instead of 5 I use now.