Hi, I have 2 questions.

1.In a homemade rack, how do you get the spacing between the tub and the next shelf to be so that the tub slides in w/o touching the top? I was told and index card on the tub, that didnt work because the tub still goes in uneasily. The next level I took it up a notch to a piece of cardboard from a shoebox, still hits the top on the way in. How do I get that 1/8" gap?

2. For ball pythons in a 41 qt rack, would a strip of 3" heat tape or a strip of 11" heat tape be better? It will be going down the shorter side of the tub. On my other 41 qt rack, I have 3" and it is fine, but I wanted to see if there were any otehr opinions on it.

sorry about the mistakes, Im rushing, lol