I have an idea that I'll implement in my next machine and was wondering if anybody else has tried it. So I was thinking of making a polargraph have a very simplified look by hiding everything except the gondola and counterweights in the ceiling. the motors would sit above slots in the ceiling of which the line/string would come through and would appear nice and clean without dangly wires and circuitry exposed. Then I was wondering on how to make a penlift without a servo wire hanging there.

Fact(mostly): a servo needs three wires to operate and a solenoid needs only two wires. So here is the plan: the string will be replaced with a high-strand-count jewelry wire that would wrap around stepper pulleys (several times to accommodate the maximum length and tied to the pulley to eliminate slipping) and counterweights would follow the same idea of being wrapped around the pulleys. The jewelry wire, being both flexible and conductive, would connect to the two wires of a solenoid on the gondola. One wire would be positive, connected to a relay of sorts controlled by the penlift command, and the other negative, connected to ground. To connect the wire from the stepper pulleys, I'll have to make an electrical bushing or something to electrify the moving wire.

I'll keep an update (pictures later too) on my progress. Ideas and tips are appreciated!