I've seen all kinds of Rube Goldberg temp controls fabricated for the 'cheap' dehydrators.

But, if you figure all the parts and labor into the job, it is likely that a mid- / upper-level quality dh with an integral control is probably a wash in cost.

My NESCO has been chugging for about 20 years, so the number of projects it has served by heating molds, drying, curing, yadda yadda ... might be pennies per project.

The lack of output is strictly on me, but I can't concieve of NOT having one.