A SOLDERING IRON!.

You guys forgot to mention the soldering iron. As durable as the plastic may be, the electronics - especially the solder joints - can be fragile! When you first open the tank, do yourself a favor and take a few digital picts of all where all the wires go. I opened up my Panzer III to fix one thing, and ended up breaking off two wires. Being my first HL, it took me 20 -30 minutes to figure out where one of them went. If you plan to be inside the tank frequently I'd cut some of the wire and add connectors.

They are easy to work on and upgrade and don't cost a lot to experiment with. Look around the forum, and you will see the results are only limited by you time, skill, and $$$.

This page has Steve and John's Panzer III mods, Merle's Jagdpanther is an extreme mod of a HL.

http://web.mac.com/ksoc/S.C.A.T./Special_Projects.html