|Crude, but obviously a tank|
First I made impressions in Sculpey polymer clay of the left and right tracks and wheels, the main hull, and the turret. This is the true sculpting part and I can't offer too much advice here without sounding esoteric...you just have to visualize what the positive image will look like while making these negative impressions. After the impressions were complete I put barriers around the impressions and filled the whole area with water-putty, creating a bas-relief-like slab with the tank's components jutting out. This is exactly how I make my spaceships now.
|Tracks and wheels|
|Blurry shot of putty masters|
The putty cured and I removed the slabs from the polymer clay. Normally at this point I make a mold of the raised part using naphtha-thinned silicone caulk. Tonight however I decided to mold with hot-glue. I neglected to get any pictures of my molds, but they were moderately detailed though nothing like silicone. The huge benefit from hot-glue molding however is the short preparation time: 10-15 minutes for the glue to cool versus the 24 hour cure time of silicone.
Since I could tell the molds didn't have the detail I wanted, I decided to continue experimenting, this time with casting material. Keeping with the theme of speed I mixed up plumber's epoxy and pushed it into the glue molds. Plumber's epoxy may be grainy, but it cures rock-hard in 5 to 15 minutes. When the parts cured I pulled them from the molds. Due to my lack of mold release on the putty masters, the hot-glue molds had putty in them, obscuring some detail. Still the parts obviously represented a tank, so I assembled them (with more putty) and added the gun barrel. With a paint job and about a meter distance from the observer I don't think it would look too bad.
Although the model above is extremely crude, I'm pleased. I know that the tank's details look poor because of the molding and casting materials, and I know from my spaceship building that the silicone-resin combination, in contrast, preserves very sharp details. And although the blurry picture of the masters doesn't show it, the putty sculpts are nice and sharp. I've never made ground vehicles before, only spaceships, but the techniques carried over nicely. So hopefully I'll find some time in my schedule to make another master (I want bigger tracks), make a proper silicone mold, and cast in resin.