manthing built us a new convection solar dehydrator. We had found some plans for this online and although we didnt want to use the cardboard boxes decided it was feasible making it out of wood so that it is more permanent. This can also be used to raise bread dough by simply putting water under the tray.
The bottom chamber has black plastic on bottom as you can see. there are holes drilled at the bottom and the top of the chamber to allow airflow,as the chamber heats up hot air is forced into the dehydration chamber where it circulates through and gos out the vent in the top.
The food tray is lined with screen and is about 6 inches above the bottom of the dehydrating chamber,the chamber bottom is black plastic as well.
We have LOTS more of the same size trays so he can build frames out of 2x4's and just stack them as high as needed then cover with the top.
this project took about 4 hours, We got the plans from this site,
SOLAR DEHYDRATOR
The other plan we considered was this one,
http://www.ag.ndsu.nodak.edu/abeng/plans/6244.pdf
we just felt that the one we made will be more efficient
pdf's about food dehydration, faq's, indoor/outdoor drying etc...
compiled and written up by University of Florida.
http://www.canningpantry.com/dehydration-of-food.html