I bought a new radio console floorplate from Jottodesk, so I didn't even have to drill holes in the car. Two holes were drilled in each can to mount to the floorplate. I also found cup holders meant for boating use, so even a large 30oz tumbler will fit.
Ham radio is a hobby, so I mounted a radio in the front can which allowed me to cut the entire side of the can away to allow adequate cooling of the radio.
Finally, the cans are all offset slightly to allow use of the latches to keep the covers closed firmly.