How to make a simple dehydrator (drying box) with a solar vacuum tube
A short and probably overkill post for a passive and zero carbon footprint drying box (not counting the required one to make the tube).I use a spare, high tech and powerful vacuum solar tube, but it is easy to make something with a copper or steel tube painted in black, around which you slide larger transparent plastic bottles. Such insulation is required to avoid the ambient air temperature from cooling your own heated air.
The second required item is a brand used low-tech cardboard box.