On one end cut a hole with a hack saw. I cut a 6"x6" . I sanded the hole to make sure there were no sharp edges
The deck box is double walled. When the hole is cut this exposes a hollow space. I used the foam sealant to plug the hollow area. The sealant will expand out into the hole. This excess is easily cut away with the hack saw after it dries
Cut the female end off the extension cord. Strip the wires and attach it to the ceramic fixture.
I mounted the ceramic fixture in the lid at the opposite end from the entrance hole. On the inside of the lid there are "ribs" . I used toggle bolts to attach it . I had to cut the bolts short so they wouldn't puncture the top.
When wiring the fixture be sure that the hot (Black) wire is to be attached to the Gold contact, and the Neutral (White) wire is to be attached to the Silver contact, and of course the obvious, the Ground (Green) wire is to be attached to the Green contact.
If unsure about wiring, have an electrician do it for you
attach the metal reflector. It isn't designed for this fixture so I used some of the left over wire from the extension cord to attach it
Hook up the thermostat. I hung it a few inches off the floor in about the middle of the front wall of the box. Plug the heater into it and plug it into the extension cord. Set the temps.
I use this thermostat from Columbus Electric:
The cords keep the lid from closing tightly. This allows air flow.
The finished Product:
The deck box
The heat emitter