A couple of mechanical challenges when building this:
- Attaching the bearings to the pvc pipe so they do not move.
- keeping the belt on the rollers
- keeping the brushes in place
- attaching the bottom roller to the motor
These are not really challenges for those that are mechanically inclined, but I found mighty-putty to of use in a couple of places.
Lets start with the metal globe at the top. This is essentially 2 14" steel salad bowls from ikea. a hole is cut in one of them for the pvc pipe to fit into, and they are taped together inside and out with aluminum tape. after you cut the hole, use a file to take off any sharp edges with a file.
A toilet flange holds the pvc pipe upright. This is bolted to a wooden base, purchased from the IKEA damaged goods section. The brushes are made from braided copper grounding wire. Aluminum tape holds the brush in shape, and a screw/washer attaches it to the pipe, allowing you to align the brush before assembly.
The latex belt is made from one of those pilates yoga straps, but get the heavy-duty-tension version, for more durable, thicker latex. After the rollers and the bearings can be mounted, you will have an idea of how long to cut the belt. Make the belt 10% shorter than it needs to be, so that it will stretch and have some tension when it is on the rollers.