I'm hoping to make my first Pepakura ODST suite, but have a few questions and want to get my facts straight.
Firstly, I'm working out of an apartment so I want to avoid odors as much as possible. From my understanding epoxy is viable for the base coat and is less odorous. What I don't know is if epoxy is advisable to be used in fiberglassing or making Rondo.
Second, is I'm not entirely sure when to fiberglass vs Rondo vs Bondo. Feedback on where to use what would be greatly appreciated. For use context, I do intend to be wearing the suit for medium periods of time, maybe a couple hours or so.
I can't help with avoiding fumes. But with regards to the fiberglass vs rondo vs bondo:
Fiberglass will generally be in the form of fiberglass cloth or mat. This will be a flexible "fabric" made out of the fibers designed to be coated in a polyester based resin (often sold as "fiberglass resin"). The combination of the two components makes a strong, rigid layer that provides significant strength to the inside of the piece.
Bondo is a brand more than a product. You will hear people on the forum use the term bondo to mean "bondo brand autobody filler". It's basically a paste that you mix with a hardener (all comes in the same box) and then spread onto the armor piece. Once it dries it can be sanded. This allows you to make smooth curves on top of a paper base (which usually has sharp fold lines and edges).
Rondo is a mixture of the bondo autobody filler and the resin component of the fiberglass step. This makes a more watery slurry that you can slosh around and coat the inside of a piece with. Generally it doesn't sand well and won't stay where you put it if it's on the outside of a helmet for example.
I do 2 layers of just resin on my paper craft on the inside and the outside before adding fiberglass. I then do fiberglass in the inside. I have been doing only one layer but two would probably be better on like a helmet. I then usually use rondo to cover the fiberglass. I mostly do this for increased strength and to cover any residual pokies from the fiberglass.
Then it's bondo on the outside to smooth over any surfaces that are meant to be curves. Put on a layer and sand it smooth. Repeat this for the rest of your life. Eventually, when you are old and ready to die, you can do some spot filler to fill in the residual defects in the bondo. This creates a totally smooth curved surface. Some people leave some of the defects so that they can use them as "battle damage". There are a lot of build threads that go over the bondo process, but they are usually pretty old. My ODST build is one of the more recent ones since most people nowadays use foam and/or 3d printing. Though, you can use basically the same process to strengthen and finish 3d prints if you want.