Taking PCB making up a notch with a toner transfer machine made from broken paper laminators.
Mechanical challenge: Default laminator feeds paper quiet fast. For toner transfer we need to slow it down like 4 times or so. It's synchronous motos running directly from mains, so there is no simple electronic solution to slow it down. A bit of fiddeling with spacing, rearanging gears and driving two laminators with only one motor makes it slow enough and still fits together.
Electronical challenge: Every laminator has heating element and thermoresistor. Microcontroller (ATMega328) controls each heating element via relays individualy and reads temperature from thermoresistors. After some trials temperature for all laminators was set to keep about 180C.
Added feature: After initial power on microcontroler turns on one heater and waits for a temperature reading go up. It repeats steps for all heaters and maps heaters and coresponding thermoresistors.
The code: You can find source code at github: https://github.com/makerspacelt/pcb-laminator