Good find on the beveled washers. You will still need to drill and tap the hole in the top of the rod. Not sure if that counts as machining....
Anyway, here is the YouTube Video of my four skulls working together:
Sorry about the quality. It's from a laptop with a webcam. But you get the idea. The skull all the way on the right is the lead singer. The eyes are in and they blink, but you can't tell from the video. Still need to paint them and add eyelashes.
Oh, and here is the template for the bracket that I made. Print it out and make sure that the ruler in the picture is actual size. If so, the template will be actual size. The white lines at the bottom just above the feet show you where to bend the steel at 90 degrees.
TEMPLATE