A fan IN an insulated box with a heater on the bottom.
I had a multitray dehydrator but it was too small. and it did not have enough airflow. But if I added air flow it would get to cold.
So:
I bought a large square window fan.
I bought the largest moving box I could from UPS.
I bought a couple of wire stands from the dollar store.
I had a temp control for a seedling mat.
I had silver reflective insulating panels hanging around (what, doesn't everybody?)
I taped the reflective panels to the INSIDE of the box.
I Gorilla taped the wire stands to the back of the fan and layed it flat in the box, now with enough clearance underneath for airflow.
I placed the heating element from the dehydrator under the fan.
I controlled it with the temp control and kept it at about 110 degrees. Most of the time the heating element was off, the heat from the fan keeping the box warm.
I had a bunch of wire baskets that I bought from the dollar store. On each harvest, I'd use a bit of tape and package whatever could fit in a pair of trays and tossed it on the fan. since I was pulling multiple trays daily, I always had a bunch of baskets in there. It ran 24x7 for months.