>>I am wanting to build some for you colombian redtails and maybe a larger one for brazilian rainbow boas.
I think a 50 gallon size tote would work okay for something like a smallish Brazilian Rainbow Boa, but will likely only be useful as temporary housing for a Redtail.
With this design [R'maid 50 gallon totes laid on their side], I found that they didn't support a lot of weight inside them very well. The 'bottom' tends to sag if there is a lot of substrate or a large heavy animal in the cage. You could get around that by supporting the bottom on a shelf or something but it strikes me as real limitation - ie. if you're housing something so big that it'll make the bottom sag, you should house that animal in a larger cage to begin with. I used these mostly for small/juvenile snakes and small lizards. Currently only one cage is occupied by a Northern Blue Tongue Skink - the other two are empty.

This type of design works well for arboreal species of lizard or snake, but again, we're talking smaller species of snakes - ie. ones with an adult size of no more than about 3 feet in length, but even that seems a bit small to me. I'm all about providing cages that are as large as possible when possible.

Where I've deemed a 50 gallon tote to be too small for a given species, I've begun to experiment with larger totes. This is the IRIS VE175 which measure something like 52x20x14 with actual interior measurements on the floor something like 48x18x14. Again, this to me is workable for a smallish python [eg. Ball Python] or a medium sized colubrid [ratsnake or kingsnake around 3-4 feet], but again a bit small for my thinking. I use a lot of different totes for my caging right now but more as an expedient until I have the space and workshop facilities to build larger caging.

All I'm saying is that if you want cheap cages, this is the way to go, but they're only adequate for certain species or as intermediate cages for growing animals. Before you put a lot of time and effort into making a bunch of these I'd look at other materials and options as well.
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Matt Campbell
"I only went out for a walk and finally concluded to stay out till sundown, for going out, I found, was really going in." John Muir