ּSuper cool! I like the trombone tuning mechanism, very clever. How do you move the copper insert up and down?
The Large loop i just adjust by hand with an analyser :) but the Idea is to use a nut melted in to a plastic chopping board and a length of threded bar connected to a cheap e-bay 3.5rpm motor. On the small loop you can see the pice of Ikea choping board i have drilled a hole heated a nut and plunged it in to the plastic.