I'm picking up my first BP tomorrow, a cute little Butter. I have her tub set up now, but it's not in its permanent state... for the time being, I have a heating pad on the warm end (warm end temps are 27 to 32). This is just a temporary measure until my FlexWatt arrives. Here are some pics of the setup so far.

I got a 32 L (34 Qt.) Sterilite tub and melted some holes into it. Then I covered some sides with black paper. The white covering is a bubble-wrap type insulating material with foil on the inner side (that's on the cool end).


This is what it looks like on the inside. The water dish is on the warmest side, to help with humidity.


And here is a picture of the snake itself! (Sorry for the phone-camera.)


I'm mainly concerned about the temperature. I've been reading the heat output from the heating pad with a temp gun every hour or so, and it seems to be stable. I've also blocked off the coldest end of the tank with some empty mlk cartons since the pictures were taken, to better insulate the air space from the cold. Any thoughts on the air holes would be appreciated, too. I think I put in a lot, but I'm not sure.
Also, I know this is a bit larger than the usual tub size reccommended for babies, but this was the best my local walmart had. I figured I would just put in extra hides and cover the enclosure with something to make the snake feel more secure. What do you think?

Many thanks!