Having built a couple high precision resistance standards, I can tell you that something as soft as a spray coating of Krylon will completely destroy the stability of the standard. The ones I built used a bite of wire, held at one end with a piece of thread, and loosely wound on a brass tube. I think I threaded the OD of the tube so the wire would have a nice predictable place to sit. IMO, you could do a great job with the KVD using wire, but for one problem. To get any sort of higher values using wire, you have to go to a really small gage. That still means a huge number of turns and working with the stuff is no picnic. Don't over estimate the inductance cancellation of the various winding schemes, as they work less well than you might think. Flat windings on mica cards are easiest to build. I've used other things as well, from pieces of PC board, to metal, to plastic. I saw a new (to me) form in diyaudio.com that I want to try. It was essentially two small star shaped pieces, with a stand off in the middle. The wire was wound top to bottom around the outside, with a phase shift between the legs of the top, vs the bottom. This gave a winding very similar to an RF inductor, where the wires are never close and parallel, but cross each other at an angle. It looked like it would give far less inductance than the various old fashioned ways you find in the electrical measurement texts like Stout, Laws, Farmer, Harris, Terman et al. FWIW, I don't think the high temp bake is as critical as for under 1 ppm standards like the Thomas resistors. Also, for whatever reason, people seem to use manganin for low resistance standards and Evanohm for higher ones. There are some really good "800 series" wires from Kanthal (formerly H.P. Reid in Palm Coast, Florida, USA) that have both low TC and low thermal emf to copper. So who's ready to machine up some tellurium copper binding posts?