Before leaving for Ghana I started using a small propane tank top heater to cure epoxy. At the time, I was working in a less finished and less insulated garage so I had decided not to heat the whole garage. Instead I built a tarp tent around my work and put the the heater in there. It was a pain.
I tried that again this fall, but knew that it was going to be a terrible way to get a lot of work done. So I upgraded to a diesel forced air heater and went from 16,000 BTU to 80,000 BTU. Now I could heat the whole garage!
My normal routine is to work with the heater off for most of the day (avoiding the fumes) and then epoxy at the end of the day. Then I run the heater overnight and get the garage temp into the mid 60s for curing. That routine costs $10-11 per day in dyed diesel. So it’s not cheap but it works.
I crack the garage door for combustion air ventilation but the cold air at ground level prevents the thermostat in the heater from ever shutting down (since it is sitting on the ground). So I built some baffles out of scrap wood to redirect the air. It’s working well now.