Note: I'm going to get this out of the way first. This isn't a good idea. I do not recommend you to build one of these yourself. I play with mains power, and am heating a box made of flammable wood. I am only showing my process and the steps I took here. Under no circumstances should this be considered me telling you this is something safe for you to build.
I built TheBox over the course of a week or so, I'm still making changes to it but it currently can get to an internal temperature of about 150ºF and keep it there.
Originally, I used a heatgun to warm the thing up. That did alright but I was worried about it running for long periods. picked up a toaster oven and ended up just putting it in the bottom of the box.
Here's an action shot of that with my first test of beef jerky.
While that did get it up to 140 without the extraction fan on, it's not the most elegant solution. Time to take that sucker apart.
I've got the cables to the controls extended and put out through the air intake. Some high temp insulated wire and crimp connectors did the part. Looking at it, the timer dials on the toaster seem to be a simple SPST switch with a spring. may be able to get rid of that. I might actually just do a way with any of the control knobs. The whole box runs off an inkbird temperature controller. This is a temporary box to hold the angry pixies for now.
Next step is insulating the box and adding some concrete board to the bottom to fireproof it a bit better. I still would not let this run without direct attention.