A slightly fexible metal bracket embedded in JB weld attached to the body inside, covered by "pretty filler". Jbw also does well for making screw boss repairs by itself or with threaded inserts. I have a tender and control units that I used jbw to do extensive repair to. The color can be a good match with care. I'll post two repairs you can see it on.
"Creative filler"-Id like to see this detail painted as extremly destressed, & weathered, a raw steel or flat black paint like the Stealth airplanes. Rocket nozzels in the back, maybe bumpers off a toy Cadillac And the front: gun pods or some post apocalyptic spikes.
Why not? If having arcuate PW is wanted, youre hunting another shell at least anyhow; have some fun with the play aspect and some paint. If you need the chassis later your ready...if you don't fall in love with your creation, lol.
There's always styrene and filler too. A least its mostly flat panels.
JB WeldNever sanded sanded, and a bad color mix too. A huge chip gone, spider cracking would have ended this one.
A better series of 3 mixes. The whole step and riser is JBW as well as 1.5" of sidewall corner, right to the rivet line. The first two areas, a perfect color match
The last coat was a little light, but hey, I didn't have to paint and still could, further smoothing this.( remember how harsh the camera is; in person, you can't tell without very close inspection.
Here you can see wall thickness on my side is thicker and cruder.
The forward risers to the edges of the firemans step is JBW, the tread top is original, but was hanging into space at first. I form with plastic wrap and lift when partially cured (there's a perfect release time, too short it mushes/stretches the mold, too long it sticks in wrinkles, a tiny pita) I form on it and/or plastic wrap with wet pottery tools, and wet fingers sometimes, once soft but partially cured that is.
The frame is wood and on it an old caboose frame split for length. Bracket for weight and to staighten a slight twist warp in the wood.
You can also lightly coat a heavy threaded screw with grease or oil and surround it in JBW. It should mold theads as it sets up and release the screw if coated well.(best for stronger items due to screws sticking sometimes on removal. Test the method a few times.)