Long ago, I had a Antex iron with just a simple heater, no temperature control. I didn't want it to run full strength all the time, but I didn't want it to get cold either.
So I made a stand where the tip rested on a wire frame and operated a microswitch. Across 2 pins of the microswitch was a diode.
When the tip was resting on the stand, the diode was in-circuit, so the element only got half the AC cycles and ran cool. When you lifted the tip, it got full power and soon warmed up.
This worked reasonably well. It wouldn't work with a temperature-controlled iron, though, as the thermostat would try to make up for the lower power.