Here's a type of Rube Goldberg machine that I've been working with for about a year. I got into these in part from a very large work I saw displayed in a museum, a piece by George Rhodes called "Science in Motion" using billiard balls.
I've completed two of these, and have a third, more involved one, in the works. I use copper house wire, 10 gauge. I buy it off the shelf and strip the insulation, which actually doesn't take all that long. The wire is then hand-formed and soldered. A friend of mine designed and created the base for this piece. It has been cross-posted to the sculptors LJ. I hope photos are okay here, and I hope cross-posting is all right. Please let me know and I'll amend if necessary.