Using Bondo Exclusively

[Darth Cal]

So I’m building my first helmet, and I used a store bought Darth Vader helmet for the mold. I’m using Bondo only, and I have so far got the rough shape of it.

Here’s my question, if the shape holds and I’m able to make it with just Bondo, is that okay. I know most people seem to use a paper base and then use fiberglass resin with Bondo on that. Am I losing any significant amount of durability, or is there something else I’m missing if I don’t do that step? Also, could I coat the inside of the helmet with resin to reinforce that part, or is that not a good idea?

Heres a couple pictures of what I have so far. I know it looks pretty bad, but I’ve added a second coat to the top that was much smoother, and I think I’ll be able to fix the unevenness of it all.

 

[Chooka]

I’ve never used Bondo on that scale, but they even in the kits for cars, if there is a straight up hole they supply a metal screen for support.
with all that in mind, depending how thing it is, it may hold. Though it may be heavy as hell lol

 

[PlanetAlexander]

Welcome to the 405th! From what I understand Bondo itself is pretty durable, though it never hurts to add some resin/fibreglass to reinforce it if you have easy access to it. Just don't expect it to hold together if dropping it on concrete. Why so much though? Generally I've only seen and used it to either fill in imperfections or round off large surfaces (such as Pepakura builds). If you're looking to change the shape dramatically, one method I'd suggest coating it in foam (such as expanding foam), shaving it back to the right shape and then going over with Bondo.

 

[TurboCharizard]

I'd agree with Chooka that this may not be the best way using purely Bondo since it's rather brittle on it's own but adding a mesh layer at different thicknesses will help overall. I've seen kits that come with a wire mesh for large autobody repairs but you could also go with a fiberglass layer and make a shell that the Bondo uses for structural support.

 

[Cadet]

I have seen pure Bondo sculpts of Helmets and Armor, but those were primarily for being used as the master for a Mold, Vacuum Form or Resin casting, because Bondo on its own can get very heavy, very quick and can be brittle and sort of fragile on its own. That is one of the reasons that on a Fiberglassed Paper Pep build, the Bondo is used in small amounts, in thin layers, to smooth out curves or add details.