this is where I got mine from

Hi thanks for this interesting thread.

I am wondering if an inexpensive bi-metallic or capillary thermostatic switch would not suffice, eliminating both the controller and relay? There would be fluctuations in temperature of <10°c but couldn't the cutoff temp be increased slightly or the time be extended to compensate for that?   Do you use the Omega's PID control function?

If the fluctuations of a bi-metallic/capillary thermostat are too wide then a simple thermocouple, an Arduino and a few lines of code could be used to control the relay for consistent temperature control at a small fraction of the cost of a PID controller.

Theres many ways to skin a cat, just depends how involved you want to get. Reliability was key for me, I didnt want to be messing around with things not working as expected. A PID isnt a huge expense, even for the Omega controller. If you want cheaper, just get one off ebay for 30 bucks. But from my perspective, you can easily bin $500 of pre-preg if things go wrong, so a good controller is just peace of mind.

10° fluctuations are massive. You ideally want to be within 1° of your target temperature if you want repeatability and reliability. 10° can easily be the difference between a great result, or a destroyed part and mould because you went beyond your moulds Tg. 

Hi ,
Thank you so much for such valuable info!
Is there any way I could see the photos again. Sorry I am 3 years late.

I want to know which model of Omega CN7800 you are using, can you tell me? Thank you.