This is a hotbox I built that I think works pretty well. To keep it lightweight for moving around in my basement I used 3/4″ board and a thin, veneer plywood to build the box. Basically, making a hotbox consists of these steps:
- Build a box
- Insulate said box
- Figure out how to get heat inside the box (I used 500 watt lightbulbs)
- Add an air circulation system (I used a fan from an old computer that was being tossed)
- Intersect the power to the heat source with a thermostat that cuts power when the desired temperature is reached (usually somewhere from 95 to 135 degrees F.) and kicks back on when it drops below a certain range.
- Talk incessantly about your hotbox to EVERYONE.
The inside is insulated with a metallic surface bubble wrap that I got at a Home Depot or Lowes. The thermostat wires to four 250 watt bulbs at the bottom of the box, and can be set to kick on and off if the inside temperature changes by as little as one degree. The fan is from an old computer — you just match the DC requirements on the fan and buy a transformer on Ebay or whatever to provide the same current. So, when I turn everything on with the surge protector, the fan stays on always circulating the air, and the thermostat lights up the bulbs until a given temperature, then turns them off when the inside temperature gets too high and back on again when it dips. For hotboxing I usually set it to about 135° F with a 2° thermostat range. I actually end up using this all winter because my basement is cold, and it saves me a ton of time to set this to 95° F, throw a bunch of skis in there, and then iron them when they’re all toasty warm already.
If you want more information or better drawings, let me know and I’ll send you something or put up some better information here.