Those can't be very effective... USB power is limited, and Peltier effect coolers are VERY inefficient. There's also very little contact area between the cooling surface and the can. I've got a desktop cooler/heater that is fan-cooled and completely surrounds a can, and it is barely adequate; it pulls about 20 watts, (USB power is limited to something like 2.5 watts). If I'm patient and the room is cool, it will chill a can to the point where ice crystals form. Mobicool D03 AC/DC Can Cooler
I'd consider adapting a cooler module salvaged from a full-size cooler; I figure that much cooling concentrated on one or two cans should be very effective. The tricky part will be coming up with a properly curved chunk of metal to transfer heat from the can to the module.
Might need some kind of aluminum sleeve or something to increase the contact area with the can. If you look at the bottom of the can, the surface area that's in actual contact with the plate is really small.