It's been cool here recently (ambient around the clonebox is 10-13C @ 70-80%RH), so I needed to work out a way to warm up the clonebox a little. I added a cheapo 150mm desktop circ fan to the clonebox as shown.
Points upward, away from the plants.
Fixed to the wall by running screws straight through the fan's plastic base. It's SO much fun to drive drywall screws through a brand new piece of electrical equipment.
Moves the air around enough to circulate a little heat from the fluoro ballasts, enough to trigger the thermostat often, holding temps +/- 0.5C from the 26C setpoint according to the peak-mem thermo-hygrometer.