I have to agree with Chris. At the very least if you go with a latching lid put some heavy books on top of it. I sometimes keep snakes (including BP and carpet pythons) in plastic boxes with lids while I build new or better racks, but I always weight them with something. It's not really hard or expensive to build a simple rack, especially a single level.
Here are a few pics of a couple of my racks built at home with melamine and select pine.
First, my latest rack. Ten levels of 41 qt. tubs. It would be pretty easy to adapt this to a single level design. It would only require:
2 precut melamine shelves, 16x33 from Lowes or Home Depot
6 select pine 1x4 vertical supports (2 six foot boards should suffice)
4 select pine 1x2 spacer strips (2 six foot boards should suffice)
48 drywall screws 1 5/8"



This is my preferred tub for this setup:

But you can easily use a taller Rubbermaid or Sterilite box.
These screws work well:










And a smaller three level rack:


And it's not necessary, but a bad@$$ saw makes the job go faster.

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1.1.0 Hondurans Het Amel
1.1.0 Hondurans Anery, Het Hypo
0.1.0 Honduran Hypo
0.1.0 Honduran Hypo, Het Anery
0.2.0 Pueblans
1.0.0 Pueblan Hypo
1.0.0 Thayeri MSP
0.0.1 GBK Blair's Phase
1.0.0 California King
0.1.0 California King Blue-eyed Blond
0.0.1 Speckled King WC
0.0.1 Jungle Carpet
0.1.0 Ball, Normal
1.0.0 San Diego Gopher, Poss. Het Applegate
0.0.1 Sulcata
0.1.0 Girlfriend, Caucasius Mexicana, Fiancee Phase
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