Hi I'm wanting to make Ebony and Ivory pistols from pepakura and wondered if anyone had suggestions on strengthening pepakura props like guns? With armor and helmets you can fiberglass the inside for extra stength, but would using resin/bondo/etc on the outside of something like a pistol work out?
Weapons can be tricky; I use a heavy paper stock when building, and then apply a couple of
light coats of resin to the outside. Less resin per coat is better to prevent deforming the piece. After resining, I do one of two things.
If it's a larger piece that has a bit of interior space to work with, I'll actually cut the pep in half and apply fiberglass matting (or cut up cloth) and resin to the inside of each half much like I would on a helmet. Expanding foam can be added as well, but you have to be careful to keep the seam area clean. After the interior is fiberglassed, I fiberglass in tabs (popsicle sticks work) along the inside edge of one half so that half of the sticks are protuding from the inside. After those are hardened, I just dry fit once to make sure it looks good, then apply resin and wrap of mat to the tabs and push the sides together while still wet. Sometimes the mat will try and bunch up, I snip off any excess that might get in the way and just try to get my seam as tight as possible. Once the bond has cured pretty well, the seam can be ground down a little and then bondo'd over to hide it. If expanding foam was already put in the ends, it doesn't hurt to drill a small access hole and spray foam into the join area to further strengthen the seam. Don't go crazy with the foam though; it needs oxygen to expand, and adding a ton will only create a perpetually wet (and heavier) glob of foam in the middle of the pep.
Speaking of drilling access holes, the other method I use is to slush cast the inside. Essentially you're pouring your resin mix into the inside of the pep and then slushing it around everywhere to get an even coat for strength. Super handy on small weapons like pistols. So, apply a couple of coats of resin to the exterior of the pep like above and let cure. Then drill an access hole in the pep (preferably in an inconspicuous place like a pistol's butt). The bigger the hole, the easier it is to pour in resin, just remember you have to fill that hole later. Then just mix up your resin or better yet rondo (resin-bondo mix) and pour it in. You're not filling the pep, just coating the insides, so don't go crazy with the pouring. After it's poured in, stick a piece of masking tape over the hole and start 'slushing' your piece around, rotating it and turning it over. You're trying to get the resin or rondo to coat every inside surface, every little movement helps. I keep a finger over the taped hole to prevent leakage, and also keep masking tape close anyways- sometimes a pep will have holes that leak resin, it's easiest just to throw a piece of tape over it while slushing. Once the hardener starts kicking in, pull your tape off.
I slush twice for strength, it all comes down to strength versus weight. If the access hole is too big to just skim over with bondo, I cut a small rectangle of foamboard that can be dropped through the hole. Poke a hole in the middle of it, thread a bit of string through, and knot it on the other side so it won't pull out easily. I take this little swing-looking piece by the string, apply hot glue or resin to the top of the foamboard, and feed it through the hole. Then it's just a matter of pulling it up against the bottom of the access hole and letting it dry before cutting the string. The 'swing' works great to back even large holes before they are skimmed with filler.
this will be my first attempt at a project, going to attempt the foam route.
