I made a cookie tin heater today, but didn't use lamp parts. I found a thing that has a light bulb socket on one side and a plug in for the wall on the other side, no cord involved...it is like you are plugging a light bulb into a wall plug. Anyway, I bought one (97 cents!), also found 40 watt appliance bulbs there, said on the package could take the cold of a refrigerator or the heat of an oven...so should be able to take any built up heat inside the can. I just used a hammer and a nail to start a hole, then found a metal 'punch' in my DH's tool box to enlarge the hole, then used wire cutters to enlarge the hole enough to get the plug in part of an extension cord through it, pulled it through leaving the extension cord plug inside the can. I was going to use my drill to start a hole, but as usual...battery was down, so not being the patient person I need to be, I improvised. Screwed in the bulb, plugged it into the extension cord, light came on, set the waterer on top. I plan on making another for my other waterer and hooking them both up to either a timer or a thermal cube. I have to leave town in the morning and coming back Sunday, so I wont have to worry about them having frozen waterers! Yay!