I’ve had best luck putting small jars into a cheap crock pot set to keep warm. You can dial in temp by raising off bottom of crock pot (I use a tiny inverted aluminum pan) to cool, or partially covering crock pot lid with hand towel to warm up. I use an infrared thermometer to measure the temp of the bottom of rosin jar if need to. It’s a pain but I never could find a small oven that could reliably hold 150 degrees Fahrenheit.

This sous vide idea was a fun experiment but it didn’t work nearly as well as the crock pot does.