There is a video on TOH which shows how you can replace the vent of a radiator with a thermostat that shuts the individual radiator off when the preset temperature is reached.
They used to have comments which identified the make of the thermostat, but they are gone.
All I can find seem to be ones that attach to the valve, if I am not mistaken, and I am not sure those are as simple to install.
I have a single pipe steam radiator. Any suggestions?
You can find this stuff everywhere in Europe, here the you need to go to specialty stores to dig them up!