I bought a simple "infrared oven" on the internet for about 20 euros. The main criterion for this model was that it is small and has a power per volume ratio of more than $100~\mathrm{W/liter}$ (Power $P=800~\mathrm{W}$, volume $V=6~\mathrm{liter}$). My impression is that they call it an infrared oven just because there are no parts that may increase heat transfer from the heaters to the air in the oven, so a great share is radiated to the walls and whatever else is inside. Measurements show that this is indeed the case (more on that later). Here is a foto:
The modifications I made:
- removed all plastic parts (some were holding the glass, so I replaced them with aluminium strips),
- removed all electronics: Timer, heater selector (off/top/bottom/both) and a temperature switch which was supposed to cut power to the heaters when the oven wall was above $180~\mathrm{^\circ C}$,
- added two type K thermocouples (I had no specific reason to choose type K, just had them lying around)
- connected both heaters to a cable for external connection,
- added thermal insulation (ceramic wool; glass or rock would have worked just as well) inside where there was room, and on the bottom (see below).
This is a picture of the bottom where I had to add "external" thermal insulation:
And here are thermocouple and heater cables:
