Also, one of the big drawbacks here would be that consumer printers would be relativly small, while the bits that you'd want to print tend to be relativly big. Most of the homeprinters I've seen would for example not be large enough to print a full facemask or helmet which would be one of the more obvious things to print for something like costumes. So you'd need to print in a lot of smaller parts and then put them together, creating weakpoints and requiring a decent amount of mechanical skill, especially if you have to also design it yourself. In contrast buidling something out of cardboard, papier mache and some home depot stuff seems easier for a novice at least.