I have seen several functional composite oven builds, made from "hot-air type" old kitchen ovens .. All the bits you need are there, except for a precise temperature control ..
This can be bought on DealExtreme or Ebay -- but you do need some electronics/electrics skills to get it to work .. Also acute awareness of the dangers inherent in heating stuff in confined areas with mains voltage electricity ..
Insulating the oven "Box" well will make the temperature control much better and save on the electricity build ..
Also build in a "door open" microswitch, that stops the fan and powers off the heating element, when opening the door(s)
(Not so much for safety, but to prevent the oven from trying to heat your workshop to 120 degrees C. when you forget to close the door ..
)
"Sapere Aude"... Dare to KNOW!
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