I have been looking for a "bargain" plug in dehydrator to make some prep "snacks" and ran across this thought it might be a neat build for you hunters - make deer jerkey etc. especially in the event of a SHTF situation - plans are here https://www.villagevolunteers.org/wp-content/uploads/2011/06/Solar-Food-Dehydrator.pdf
that reminds me of the "science experiment" from 6th grade take a cardboard quaker (or store brand) oats container cut out a "window" that spans almost end to end several inches in "up and down" line inner with aluminum foil shiny side up use metal shishkebab skewer and pierce through the ends of the oatmeal container placing a hot dog on the skewer an interesting spin i just thought of would be a small solar panel that would turn a motor and have a home built rotisserie (of a much smaller scale though!)
The cheapest and easiest solar dehydrator you can make is...a cardboard box about 2' on a side. Add a couple of wire cookie racks and cut some nylon window screen to fit them. Hang a thermometer inside to keep track of the temperature. Load the box with stacked racks just like any dehydrator and set it out in the sun. You don;t need to insulate it, paint it black, or cut windows. The idea is for it to operate at LESS than 100% efficiency so it doesn't get too hot inside. Crack the flaps open a little to let the moisture vent and you're good to go. In any kind of reasonable sunlight, you'll have all the heat you need, free, almost all day long.
If you look closely at each configuration , it's not that hard to come up with other ideas that accomplish the same thing. Some folks use a Fresnel lens, from a cast-off projection TV, to speed up the process. but you wouldn't use card board , it will ignite it .
That would depend upon several factors, including the focus, weather or not the cardboard is lined with foil, (which reflects light and heat pretty well ) and the size and type of fresnel lens. Mine is @3×4 and a linear type do not quite as focused but fine for cooking.