I am trying to prevent condensation in my kegerator, and it seems that sealing it as good as possible is a great idea.
I have a chest freezer with a wooden collar where the faucets are installed and the lid is mounted on top of the collar. Should I use silicone caulk? Rope caulk? Aluminum tape? Should I insulate the wooden collar or are the boards good enough?
Condensation is usually caused by opening the kegerator and letting warmer, more humid air in.
However, getting a good seal and good insulation on your kegerator is important for keeping your energy usage to a minimum. After all, running a kegerator can be spendy.
Silicone or latex caulk are relatively easy to apply and give a good seal. Insulating the inside of your lumber is probably unnecessary. Wood is a fairly good insulator (look at log cabins - they use naked wood for insulation). If you're uncertain if insulation is necessary, feel the outside of your kegerator. If any part feels particularly cold, insulation would be helpful.
Generally, though, wood and caulk are sufficient for good insulation.
