18+ strapping non-wall mountable gear to the wall

Trying to clean up the network closet. I’ve got an S33 modem that’s shaped like an almond, and a lutron hub that’s like a deck of cards, that don’t have keyholes to mount with. I’ve seen the 3D printed brackets but that’s not my style. I’m more of a duct-tape-and-bailing-wire kind of guy. The leading plan is some...