Re: Cerakoat type oven:
Here's how to make a good one that would be commercial duty for $250 bucks or so, should be able to cook 3-5 barreled actions at once.....
Buy one of these for $100 (you can't hardly build a box for that, and the door has a good design)....
http://www.walmart.com/ip/Stack-On-8-Gun-Security-Cabinet/11071333
Strip out the guts, all you need is the outer shell. You will need to screw a small external latch on, as any internal latch will be a PITA.
For the most even temps, you would lay it on it's SIDE with the door opening facing towards you and hinge at the bottom. Heat rises and any up and down hanging of guns will result in hotter at top and cooler at bottom, this will allow guns to be hung horizontally (use a rod in the muzzle) and will allow almost perfect evenness of temperature that the gun sees.
Buy the 1" thick rigid fiberglass I described in the above post and line the inside of the box with the foil side facing inward. Glue it in with good silicone sealant. Use the foil tape to seal everything up and seal around the holes you're gonna cut later.
Drill 3 each 1.5" diameter holes across the lid and through the fiberglass for 2 purposes, to shoot temps with a heat gun and give ventilation if needed. Place these holes about where the action would hang from the wires you'll hang from the ceiling of the box. I would also put a hole high in both ends for ventilation, might not need it, but it's easy to do.
Make some little sheet metal sliding doors to cover these holes, by cutting a 2" circle of sheet metal and putting one screw at the top of the circle and screwing it to the door, then just slide to the side to open or close, or adjust to anything in between.
Buy 4 of the $20 hot plates from Wal-Mart, cut 4 each 8" diameter holes evenly spaced across the bottom floor of the box.
Cut 4 short angle iron legs to screw to the corners of the box to lift the floor of the box high enough to just barely clear the hot plates (so you can slide them in and out, under the box). The hot plates are 6.5 - 7" diameter, so the 8" holes will allow an air gap around them, this will allow the plates to last a long time and give a little fresh air for ventilation.
The plates have thermostat control knobs on the front for temp adjustment. 4 of these should allow an easy 500 deg F. inside, so you will be able to turn them down to the center of their heat range for this oven.
You can set a little wire rack inside for all the small parts.
You can only plug 2 of these hotplates into the same 20A household circuit, so keep that in mind.
This oven, unless you just want to be really cool looking, will work as well and give more even temps than any $1500 oven you can buy.
The reason is the multiple hot plate thermostats will not cycle at the same time, unlike a single element which will kick on and off at a delta temp of usually 25 deg. And you can adjust the 2 center ones a little cooler than the ends, if needed, etc.
I think handling the pre-cooked painted guns horizontally with an aluminum muzzle rod will be much easier than up and down hanging.
You could actually make a shelf to rest the muzzle rod on one end, so you wouldn't have to mess with a wire on that end.
Whew, that was a mouthful! Hope I helped you a little, if it's not what you need, maybe there is an idea or two you can use, anyway!
Edit: It would probably be easier to cut the holes in the steel safe before you put in the insulation and cut the insulation when you put it in later.
Also, if you don't like the hotplates, you could use an electric element inside, but it wouldn't work as well, nor be as simple, and I like simple stuff!
