Yard Master & Research
I have a boxcar with no doors and tried to mold one. I used a Baby Ruth shell (full side with no moving door)and with some vaseline I set it in bondo. I did get some discoloration on the car. Bondo gives off a lot of heat when drying.The picture is a cast of that mold. I had a lot of air bubbles but considering the detail it does look like a door. I used a Dremel cutting wheel to fit the opening. Also I used the wheel to chase the grooves a little.