Here is the primary coil of our old 6" Tesla Coil. It is constructed of 3/8" copper refridgeration tubing, with 3/8" of spacing between turns. The I.D. provides about 1" of clearance from the secondary coil when is is mounted in position. The coil winding itself is supported 1" or so above a plexiglass baseplate by notched lexan standoffs. The standoffs were made using a dremel tool, a vice, a drill press, and a hacksaw. (holes drilled, mount in vice, saw out notches, clean up with dremel tool)