fiberglass resin

my dad doesn't let me use fiberglass resin, so will plaster of Paris do fine?

I believe this is the third or fourth thread you've started all with similar questions. No problem with the questions, we are here to answer them and help you out, but all of this could have been kept to one thread... it's just good forum etiquette!

On to your question. I haven't used plaster of paris before, but due to its thickness and the fact it is water based, I think it would quickly deform a pepakura model, as well as be very, very fragile.

Your questions seem to be relating to the safety of materials quite a bit, so why not try your hand at using eva foam? It's relatively inexpensive and quite easy to work with! There are a ton of threads with builds using this (I have a lot of pics in the build thread in my signature) and a lot of information about where to buy it throughout the forum.

Cheers!

Plaster of paris is VERY brittle and would not hold up for costume wear. At the thickness you would need to avoid cracking it would be much too thick and heavy. There's epoxy resin which is not near as toxic as fiberglass resin, is odorless (but still follow the safety precautions), doesn't shrink, and is compatible with fiberglass cloth/mat. Some people also use wood glue and cotton cloth, which would be moderately strong but you would need to take care to not get the paper too wet with the glue or it will deform.

I've used plaster of paris for a Boba Fett helmet before and didn't find it too hard to work with. Here are some pictures of the end result (sorry I couldn't get them the right way) :



What both FlyinPhil and RobotChicken say is true, it can be very brittle and delicate. A friend made a Jango helmet using the same method but didn't use enough and fell apart a few weeks after it was made. I however I spent more effort on this one. Its a cardboard model with a paper dome covered inside and out with plaster of paris. Because you have to use water in plater of paris method the model gets very soggy. The cardboard was strong enough however the paper dome required supports throughout the process.

Eventually after about a week of plaster, dry, repeat I got this. Its quite strong (I've even dropped it a few times) and taken it out on a night of heavy drinking for a university social event, though I am fearful of it cracking wide open due to the brittleness. Its not great compared to some of the builds on here and I'd want to use a better material if I made another Mandalorian helmet but it was cheap, did the job and then some so I was fairly pleased. My number one complaint is the texture your left with (especially after painting) its not a texture that resembles a metal helmet. The second warning is the weight, it's a fairly heavy piece.


My advice is use foam or if your wanting to keep it cheap cardboard and maybe paper maché. Still here is a pic of the full costume for anyone that's interested:

Is this kind good?(cant get any more materials(dad doent like to drive me to HD any more)it says DAP PLASTER OF PARIS PROFESSIONAL QUALITY which could melt your skin off

All plaster will be brittle unless you build up the thickness so it's stronger (although still not indestructible) and that will end up making it quite heavy. If you can't use resin I'd recommend wood glue. It's strong, hard, sandable, non-toxic, cleans up with water, and inexpensive. Just be sure to apply it very sparsely until your piece becomes more rigid because it's water-based and can sag your cardstock if you get it too wet. Use can use the same stuff to glue a canvas-type fabric to the inside which should give it reasonable strength.