Based on the design of the solar dehydrator mentioned in the "A Solar Food Dryer from Cardboard Boxes" article by Dale J. Jennings (Mother Earth Magazine) I built a rather successful wood version. I prefer the wood version over the cardboard as I can leave it out all summer and not worry about rain fall. With a little scrounging I was able to use salvaged wood, an old storm window, a rectangular framed window, a heavy duty black garbage bag, some metal sheeting and some old plastic bug screen.I did not have
metal screen window screens I made those from new materials, but I would strongly suggest looking around to find three identical size that are professionally fabricated, or bring three plastic screen windows to your local home improvement store and have them professionally stretch the metal screen. Even though I have screen print and painting canvas stretch experience I was not able to stretch the wire screen without tension, which resulted in uneven screens. They work fine, but it is annoying to handle them as they want to pop back up instead of laying down flat...Have the dimensions of your box be determined by the dimensions of your three or four screen frames, then find a top window to fit that and then put together the box body. Look for a rectangular wood framed window for the heater tunnel that is similar in width as the drying screens.
I used the illustrations in the article to base my design on and as long as you have the intake on the bottom, flue on the top, with a metal sheet to guide the airflow within the drying box it should not really matter how big or small it ends up to be. Use bug screen on air openings to prevent drying bugs with your produce!
Below images of my finished project, including some of the delicious dried apple slices we made!
Front view of the dehydrator. The heat tunnel is slid into the opening on the drying box, not permanently attached. We only have to lift up and slide the heat tunnel out, to be able to carry the apparatus to the shed in two manageable parts.
The back side of the dehydrator. I attached a horizontal bar on each side of the box to create carrying handles. Since I used scrap wood for the legs I did not have anything longer than 48" but combined with the length of the window heat tunnel, the angle of the tunnel toward the sun is not ideal for optimal heat. It does not seem to hinder the drying process, though it might make it a little slower. When I find a shorter window of the same width I can make a shorter tunnel, and compare the two - it will be neat to see if a more efficient angle will make a difference.
And bon appetit! Delicious homemade dried apple slices, without any preservatives.