Being somewhat lazy
Your initial laziness will likely be dwarfed by the potential problem of transferring any collected swarm from your 'repurposed' container to your real hive.
Picking something that will accommodate your frame size is the obvious starting point. I used 14 x 12 nucleus hives with a nucleus sized shallow below. That allowed simple transfer, if shifted early, or some expansion if in situ for a few days. It also gave a volume close to the recognised 'preferred' cavity size.
So, 'repurposed' hive boxes are the obvious preferred choice. Reinventing the wheel is unecessary and it will often entail more work than taking the simple options available - and the bait hive can be re-purposed as an over-wintering hive for a nucleus colony with little effort (for a lazy beekeeper).