I've just finished a paint drying cabinet and starting to use it. I made a box from 1/2 inch particle board for the base. In the base is a lamp base with a 60 watt light bulb, and in one side I mounted a light dimmer to give me control of how much power is going into the bulb. There are holes in one side, and in the top. I mounted strips of cloth filters used for filtering hot air registers, to control dust. Over the top I have inverted one of those plastic tubs we bring models to shows in. The top, which has most of the center cut away (to let hot air flow through) holds the bottom (which is the area the model parts are put in). That has a hole cut in the bottom (which is now the top), which I put a disk of that filter material over it. The heat from the lamp causes a natural convective flow from the base through that top chamber. Right now, I have calibrated the temp in the top chamber, set to 90 F. Seems to work great and was quite cheap to make. The unit serves two purposes- a dust-free place for the model to dry in, and a heated area to speed up the drying a bit.
I have friends that use food dehydrators, but those run too hot, and some of these folks have had parts warp. That is why I included the dimmer (I think it was six or seven bucks) to allow me to control the temp.