I recently started using a Rival (there are other brands) Hot Pot to do several jobs in Lutherie. It is a wonderful tool and costs about $10.00-$15.00 at any Target, K-Mart or other store that sells small appliances. My first run in with a Hot Pot was in college, where it was used extensively by students in dorm rooms to get around the "no cooking" bans of dorm life.
The Hot Pot is nothing more than a plastic container with a heating element in the bottom. The heating element is controlled by an adjustable switch so you can regulate the heat. I fill it about halfway with water to use it.
I then put an automotive A/C thermometer in the water so can tell how hot the water becomes.
Hide Glue: The first use is relatively self evident. If you use hot hide glue (and you should) you need a way to heat the glue to 145 degrees and keep it there while the glue is in use. I prepare my glue as usual and then pour it into a small plastic glue bottle. I place the bottle in the glue pot which has been set at 145 degrees. There are several benefits to this approach: 1) The glue remains at 145 degrees, and 2) you have hot water right at hand for cleanup. The Hot Pot is a wonderful Glue Pot for hide glue and it is cheap!
Lacquer: The second use is more enlightening. I had always heard that if you sprayed nitrocellulose lacquer it would flow much better if it is heated prior to spraying. I just could never come up with a way to easily heat the lacquer to find out if it flowed better. And then: the hot pot!
Firstly I set the temperature of the Hot Pot to its' lowest setting which is about 100-120 degrees. Then I put the sprayable lacquer in the spray gun. Place the spray gun into the hot water in the hot pot for about 10-15 minutes. The lacquer will warm up to the temperature in the surrounding water. Now spray with it. My experience at least, was that the lacquer flows much better when it is warm. It seems to just "melt" on the instrument allowing for very little sanding down the road. Give it a try-I think you will be really pleased!