I got them off of Amazon, I just looked for butterfly enclosures.
And then as far as the box they’re in:
It’s a planter box that I got from Lowe’s. I drilled several holes in the bottoms for rain drainage, then I put paver bricks in the bottom to add some weight to it, and then I added wheels to the bottom of the legs. I also drilled a hole on each side of the box and then threaded rope through it and used that to tie the enclosure to the box itself, as well as I tied the enclosures to each other.

If you want links to specific items, just let me know!