Adapted from these plans. Our dehydrator is slightly smaller (five feet rather than five feet six), to allow it to be cut from four (rather than five) sheets of plywood. It also uses less wood for the internal skeleton: it seems to me that the plywood box, glued and screwed together, is going to hold this thing in place perfectly well, with only a little corner bracing to keep it from twisting.
This is a passive dehydrator: the sloping "pouvoir" (power, in French) sends heated air up the chute, which then descends inside the box, drying as it goes. The cooled, humidified air exits via the north side chimney.
Both of these braces could be moved to the outside, and that might be preferable to reduce obstruction of the airflow. In this event, the south posts could also be reduced by two inches in length, to allow pure air flow.