What I used:
2 cardboard boxes (one large enough to hold drying racks, and one shallow one to collect heat)
Black Non-Toxic Tempera Paint
One Large Ziplock Bag, cut open (plexiglass or saran wrap will also work, anything clear to create a greenhouse effect)
First I taped up the large box. Then I cut a large door on one side, and small vent holes at the top opposite the door. Then I cut larger vent holes in the bottom of the box where my "heating box" will be attached.
Next I cut the top off the shallow box, cut off one side at a 45degree angle, and cut small vent holes in the opposite side. These small holes are where air will enter the box, become heated, and rise into the dehydrator box, drying fruits and veggies, and then rise out the top vent holes carrying moisture out with it.
I painted the inside of the heat box with non-toxic water based black paint and then I taped it very securely below the larger box, centered over the vent holes. I used the leftover cardboard from the heat box to make 2 triangular legs and taped them on the opposite side. This is a very stable dehydrator, despite being made out of cardboard!
Finally, I taped clear plastic over the heat box to create true greenhouse environment. Obviously, I would prefer to make this setup out of glass and wood b/c it is A) much more permanent and B) is less likely to off-gas fumes, but I am happy with this temporary setup for now. If it works fantastically well, I will definitely go on to make something more permanent... In the meantime, I am allowing the dehydrator to off gas for a few days before using it to dry food I will eat.
Drying food is great way to save your harvest -- few nutrients are lost, and no canning means they take a lot less space to store. No freezing means they use a lot less energy to conserve. And if you use a Solar Dehydrator instead of an Electric one, you also save a lot of electricity.
I am using drying racks which I have from my electric dehydrator, places on top of a metal baking rack to insure the air flows through up through them. I did not insulate my dehydrator, although many do... I am not sure it is needed in this climate, though I suppose in cooler weather it would be a good idea.