I used to produce carbon parts a number of years ago and made my own oven. Programmable electronic control, used 2 x heating elements with fan assist, went up to around 250 c quite easy and had vacuum inside. It even turned the vacuum pump off when the cycle had finished.
The control did have a back up system to cut power if the power to the elements became locked on due to a malfunction.
The basic structure was a steel box within a box with rockwool insulation and insulated doors, it worked a treat and speeded up production.
I think it cost around £800/£1000 to make. Ran off a 3 pin plug and didn't use much electric as the elements were pulsed with power.
I sold it to some guys in Leicestershire, I think they were. They made carbon gaming chairs.
Any how it turned a 24hr cure into a 1~3 hour cure, well worth it if you need quick turn around.