You thinking of deconstructing the pallets and using the wood or leaving the pallets assembled. Disassembling pallets sucks but more freedom with the wood. If you leave them together, you should be able to get the rough framing for the floors, walls, roof? out of pallets them cover with siding/infill the gaps and roofing material. Then misc wood for boxes, roost, doors, etc.

I could see it being done and looking cool, prob take more time but might save a few bucks.

Good luck!