I recently discovered a moldable thermoplastic product called Polly Plastics (Instamorph, Friendly Plastic, Plastimake). It is a plastic that comes in little pellets and you can heat it up and it becomes moldable like clay and you can shape it into anything you can imagine and then when it cools it cools as a hard plastic. I have seen other cosplayers use it occasionally, but I have developed techniques using it to where I can make anything you can imagine simply and easy. No need for a 3D printer, you can make the piece yourself with a pot of hot water. I have made: swords, grenades, masks, helmets, armor, Pouches, Lightsabers, and many more things. There are other awesome thermoplastics such as PVC and Worbla as well that would fit under this category. I would be able to talk extensively to this subject and I feel that it is an area that most cosplayers are un-familiar with and could really blow their minds! I could do a demonstration with this as well and show how these thermoplastics work right in the presentation to show how easy it can be to work with, and how quickly you can make anything.