Any suggestions on how to keep a small quantity of liquid at 45°C for about three days?
fill a cooler with 45º water and submerge the container with your liquid. Change each day.
I have a fermentation chamber that I'd use, but it's a bit of work to make, and you'd have to find a temperature controller.
FYI I have a spare temp controller $20...
Hmmm, that might work... I don't have a problem with a bit of work, and a 20 dollar temp controller sounds good to me.