Looking for info on hot boxes for slings. Can someone point me in the right direction?

[Rowdy Hotel]

I'm interested in setting up a heated tank to house numerous slings I have and would like to read some old threads on how some other members have done it. I know there are some old threads on this but I'm having a hard time finding them with the search feature. All the keywords I try are either too short or don't turn up the correct threads. Thanks.