Hi Mark,
That's a bit of an awkward size cage in that it wastes a lot of material. I don't believe you'll find it as a stock product.
Vision makes that one cage that is 48"x28"x28". Off the top of my head it's the only commericial cage I can think of.
Or you could contact some of the other companies and see if they'll do a custom build.
Just a quick comment. If you do go the the custom route you might consider modifying the dimensions slightly.
With the size you listed someone will have to tear into a second sheet of material, assuming they work with 48"x96" stock which most products come in.
If I took your dimensions I could add 12" to the length and use the exact same amount of material. With the dimensions you listed there would be a bit of awkward sized scrap that will be of little use to the builder.
In other words, I could build a 48"x24"x36" cage for the same as the 36"x24"x36" cage you mentioned. In fact it would require fewer cuts so there would actually be less labor time.
But maybe you don't have room for a 48" long cage. Regardless, the cage you want will exceed the maximum shipping dimensions allowed by UPS, Fed-Ex, etc. You should double check that and plan accordingly.
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Current snakes:
1.1 Gonyosoma oxycephala - (Silver/Yellow)
2.2 Gonyosoma oxycephala - (Green)
4.3 Gonyosoma janseni - (Black)