Edit History

As someone with a wee bit of experience in building stuff, I'd recommend:

1. Assemble at a wood box with a hole in the top to fit a metal bowl and a wooden shelf below the bowl. Box should be about 300mm taller than the bowl, with substantial space below the shelf.  Birch ply for preference - it's a good thermal insulator. Paint it with something that'll withstand some water.
2. Fit a metal bowl with ~14mm a hex bolt on the bottom using JB weld. Center it carefully, or it won't really work.
3. Laser cut from acrylic a wiper that fits closely to the bowl. You'll likely need to add some sort of flexible wiper to keep chocolate from sticking to the bowl and getting burnt. Fit a standard K-type thermocouple probe to the wiper so the metal bit is poking into the chocolate area.
4. Fit a geared brushed (yes, this matters) motor with a socket that fits the hex bolt. Asynchronous brushed motors can be controlled with a lamp dimmer. Alternately, an AC synchronous motor of about 80RPM should work.
5. In the cavity below the bowl, fit 3 light sockets with 60W bulbs. (These can be increased later if required.) The shelf for the motor should obscure these from the bowl.
6. Fit a small AC fan to blow over the light bulbs. You're going to need one that can take a lot of heat.
7. Connect the 3 light sockets to a standard PID controller, connected to the K type thermocouple in the wiper.

This will get you a more-or-less reasonable clone of a Chocovision. The bowl and wiper sit on top of the unit; the motor sits within it to spin the bowl, and the lightbulbs and fan provide even heat inside the unit. Wood is recommended for its' low thermal conductivity and relatively low thermal density - it won't likely give you any overshoot problems.  Similar designs work for soldering work...

If this sounds like a giant pain in the rear end, I would look into getting one shipped from the USA as a used item. Some sellers will do this, and you're still under $300USD with shipping and customs.