I just won't use a tub/lid for a snake. Lots of people do it, and successfully, but it's too worrisome for me. I had a ball python in a tub with a lid, and had it secured with multiple clamps. First off, it was a pain in the tail taking all those clamps off and on when getting into her tub. Second...twice, she managed to pop a clamp off a corner and wedge herself up and out of the tub. Just recently when I moved, I had to keep my milksnake in a tub with a lid for a few weeks until we were reunited with her regular cage. I had really heavy books weighing down all the corners and edges, and even so, I still had multiple heart attacks when looking in on her and not being able to find her. (She never did escape, but sometimes she made it look like she had!) I simply would not be able to rest with something as strong as a blood python in a tub w/ lid. And if I did manage to get it truly secure enough...it'd be a serious pain in the tail to get into each time.