So my DIY masks require some clean up, flash removal, etc. This is actually very easy and you don't even need a dremel. It's a good way for beginner hobbyists to finish their mask without having to invest in power tools. You can use hobby nippers and a sculptors rasp to remove unwanted edges and smooth them. Nip off the larger flash parts first ( "flash" is extra bits on the edges of the cast piece leftover from the casting process) and then rasp off any jagged edges. Some medium grit sandpaper will smooth things down even more once you are happy with the smoothed edges. You can find smaller rasps at hardware shops if you want to get into small parts like the nostrils or use it to saw through the jaw if you'd like to try to make the mask's jaw hinged. It takes some elbow grease but i actually prefer rasps over dremels. Less noise and the dust isn't flying into the air.
If you do plan on ordering a DIY mask, please be sure to understand what is involved with buying one. Information is clearly provided in the item's listing and in the shop's blog. I do ask that the buyers have some hobby experience or are at least comfortable with learning on their own. I cannot personally teach people or provide build help beyond what i post here and in product listings.
This is a sculptors rasp.
These are hobby nippers.
(Please be sure to wear a particle mask when you sand! Parents please supervise your kids, adults please supervise yourselves by wearing appropriate safety equipment and using common sense when working on any craft project.)