>>Base temp in my house is 82 in the main house and 72 in the basement where I keep all the bugs/rodents and incubators.
So you're saying it's 82* ambient in the ball python room or 72*? Regardless, it sounds like you want something fairly simple and cheap right now so build an open rack is probably not the best idea.
>>Iris tubs aren't necessary, I'm not concerned with totally clear tubs so steralite ones should work just fine for what I need.
That still does not tell me what size tub you want. From your description below I gather you want a large box, something where the floor is about 30" long. Good idea, IMO.
Also, the Iris CB-70 and CB-110 (the typical BP tubs) are just a bit more clear than sterilites. I think the Iris tubs are worth the extra money due to how sturdy they are. They will last a lifetime. Again, if you're thinking about switching over then it might make sense to keep things cheap for now.
How about a simple/cheap rack that can hold different sized boxes?
Sterilite makes a 41 qt, 28 qt & 12 qt. series that are all basically the same height. One of the regular posters here built a rack where each tier can hold one 41 qt or one 28 qt one 12 qt or three 12 qt boxes.
There are slightly different versions of these boxes. You'll need to find the ones with the continuous rim around the bottom rather than the individual raised feet on the bottom.
Also, this means the 41 qt. and 28 qt. boxes will need to slide in width wise. I'd build the racks from melamine and plywood.
>>I plan on using the GCS 4 unit pulse proportional thermostat and flexwatt, do you think it would be better to run 4 racks off of this or 2 with 2 different zones in each because of the heat rise factor?
I think two racks with two zones is the better idea.
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Current snakes:
0.2 Gonyosoma oxycephala - (Silver/Yellow)
3.3 Gonyosoma oxycephala - (Green)
2.1 Gonyosoma janseni - (Black)
3.3 Gonyosoma janseni - (Black & Tan)