A vented dryer your only option in a well ventilated shed that has a constant year round temperature above 10 degrees C. If the temperate drops below that the electronics will fail big time. Avoid any possibility of condensation. Install a smoke detector, ensure the power supply is RCD protected and keep combustible/flammable items well clear!
In addition to Martin’s excellent advice 🙂 buy one which only has timed drying like the White Knight WK44A7W. Machines with sensors won’t work unless the temperature is higher than about 12 degrees C.