I tried that first. The problem was I cut out the battery box and had very little structural support left. The flex was too great and my magnets weren't holding.

But, now I'm worried it weighs too much and even with metal arms, wheels and treads, the attachment points will still be too weak and I'll end up tearing out the plastic.

Here's a thought:

I was reading on how to take a ABS plastic piece and by using a process similar to wax casting, you can build the mold, insert the mold with the ABS piece embedded into a furnace at 1200 degrees and it will melt the ABS out of the mold. Once the ABS is melted out, the mold is ready to receive the molten aluminum.

Carefully make the pour and after cooling, crack the mold (it's only good for one pour).

Instant ALL ALUMINUM HENG LONG TANK (about 2% smaller)!

This is also the process that is starting to be used with 3D Printers printing with ABS.

Kinda brings up some scary images (not the least is all the inaccuracies in the HL now cast in metal).

I think the HL ABS plastic is a combination of materials. Looks like I'll pass and live another day.

tjs