This has been a gratifying addition to the estate. When the garden works, sometimes it REALLY works. Of course neighbors get some overflow, but their gardens tend to be working too. Nothing would go to waste if we did not harvest, of course, but all kinds of dried stuff is nice to have: tomatoes, herbs, banana slices, mango slices, kale leaves - those are our top uses.
This is a simple design inspired by inheriting two suitable glass panes. It is a simple box with 1x6 plank sides (to make total "depth" of 11 inches (28cm). The "bottom" is a thin sheet of galvanized steel. Interior is painted flat black and it gets quite warm in there - I should measure some time.
I built it to fit some glass that was about the right size, so not really a design others would emulate precisely. But a standard sheet of galvanized sheet metal is about three feet by six feet, so four 10-foot boards will nicely make the "box". I used 1x2 for the corner bracings (just glued and screwed), window frames, and dryer trays. I had made an earlier version with a sheet of translucent corrugated roofing for the lid, and that heated up quite well, too. The legs were just some scrap - I think the angle of the box should be around 45 to achieve some natural convection and good mid-day sun collection area. But it could vary with one's latitude I suppose - in a more northern clime (I'm at 20N), a more vertical "cabinet" might work - the dryer trays would be shallower, but convection would be better. I am not sure the vent stack makes any difference.