This is my 4 inch Tesla coil.

The primary is 15 turns of 2" wide .030 thick copper strap with .5" spacing between turns. The inner diameter is 6". The supports are made from .25" Plexiglas. Inductance measured at .066 mH. A folded piece of brass shim stock is used to tap the primary.
The secondary is wound on 4" thinwall PVC conduit(4.375" OD). It's 22AWG wound for 23", a total of ~836 turns.
I'm driving this with a 15/60 NST and using .02uf @ 30kVDC of capacitors(2 panels) in the tank. The spark gap is my new single gap spark gap.
The toroid is 7" x 26.5" made with semi-ridged vent.

Measured output at present is 34". Here are some spark pictures

Some pictures during construction.