The discussion board at tk560.com is here:I will try to look at the site to see if I can have some of my students try to build this Thurson James's design of an oven. In case I can't find it, the next time you are on, can you provide a link to this discussion?
The basic Thurston James plans are in his (really excellent) book, "The Prop Builder's Molding and Casting Handbook."
Jim Egner's (tk560's) article about actually building it, with some cost-saving substitutions, is here:
Most of it is straightforward, with three exceptions.
The first is that the straight TJ plans call for welded steel frames to hold the plastic. You don't really need that, and for many people it's a problem (I don't weld, myself), but I'd guess that wouldn't be an issue for you.
The second is that the ceramic "millboard" for lining the oven is freaking expensive in small quantities. Jim E. substituted Hardibacker cement board from Home Depot, which is cheap as dirt and works fine, as long as you support it with a couple of struts across the bottom. (It's not strong stuff, and unsupported across a 2 foot span, it's likely to crack. The oven will still work, but supporting it is probably a better idea.)
The nichrome coil in the plans costs about $30 for a 10-foot unstretched coil, which is several times what you need to make one oven. (Stretched out, that's a lot of nichrome.) You can split the cost by finding somebody on the tk560 discussion board to split a coil with.
The third thing is that the little ceramic insulators for attaching the coil to the backer board are the most expensive part of the whole machine, and about half the cost of the oven.
The ceramic insulators don't appear to be necessary. The millboard or Hardibacker board can handle being in direct contact with the nichrome coil, and is an electrical insulator, so you can just attach the nichrome to the backer board with baling wire. (I think that's pretty much what Doug Walsh does in his HobbyVac plans.) The downside of that is that each baling wire attachment will be electrically live. You'll want to cover the other side of the backer board with something to keep people's fingers out of it, but one big insulator is easier and cheaper than 60 little ceramic gadgets.)