The coil taps hardware is made of stainless steel. The taps are actually terminal posts with the wire going thru the hole of the post and a screw making contact with the PCB and pressing against the wire at the same time. Very clever solution. The ends of the terminal posts are protruding thru holes in the coil form for mechanical support. The coil wire is of very heavy gauge (AWG 10, ~2.7mm diameter) and the turns are spaced about 3 mm apart for the first 11 turns by an interlacing nylon cord (something like the nylon cord from a Weed whacker) and then spaced 11 mm by small self-adhesive pads (used as stick-on feet for home electronics equipment) for the last few turns. The ends of the wire are bent inside the coil form and the ends of the nylon separator cord are melted into small blobs. The coil form looks like it is made of fiberglass-epoxy composition (I guess also made in-house) and it doesn't look very pretty - actually looks bad and unsightly - very rough outside surface and poor (flaking) paint. It appears to be very light and strong though. The look is not important - it does the job fine. The OD of the coil form is ~112 mm.