I found the design for this motor on Bill Beaty's Science Hobbyist site and just had to build one
This photo shows the finished motor sitting on top of my Cockcroft-Walton voltage multiplier, ready to run. The three, one quart, high density polyethylene bottles are sitting on a piece of 3/4" thick ultra high molecular weight polyethylene board. The two end bottles are wrapped with aluminum foil duct tape and bolted to the board with short lengths of 1/4-20 threaded 18-8 stainless steel rod and nuts. The rod on the left bottle extends through the board and contacts the output terminal of the CW. The middle bottle has three 2" X 6" strips of foil tape and is supported on a needle bearing ground from a length of 1/4" drill rod. The rod sits in a 1/4" hole drilled 1/2" deep into the board and passes through a 1/4" hole in the bottom of the bottle. The point of the rod rests in a dimple made in a piece of 1/32" Teflon sheet which is held in the mouth of the bottle by the screw cap. Taped to each end bottle is a 1" wide strip of aluminum roof flashing, with the far end bent at 90ยบ and cut to make a pair of sharp points. The right hand bottle sits on a short length of flashing which is used for the ground connection.
This is a no flash (hence long shutter time) photo of the motor in operation. The three aluminum foil sectors on the center bottle are blurred into a gray band by rapid rotation. Several arcs are visible between the left hand brush and the center bottle. More can be seen between the center bottle and the right hand bottle. This is not ideal for motor operation, but makes a nice picture. At lower voltages (~40,000 volts) there is no arcing and the center bottle spins even faster. A digital multimeter spliced into the ground connection showed a current draw of 40 mA under these conditions.
This sketch should help clarify some of the construction details I gave above.
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