The solution most appealing to me (if this was my challenge) was using
a vacuum on the outside of 1/2 of the can.

It turns out that the inside diameter of the drive shaft from a Holden
Kingswood (or similiar vintage holden) is just right to take a coke
can, slightest of interference fits (at least the coke cans and Holden
Tail shafts that I am familiar with in Australia).

I suspect one of these could reasonably quickly cut in half length
ways.  Several small 1/8" holes drilled along the length connected to
aluminum or copper tubing connected to a vacuum.  Sponge down the
"half" tail shaft to improve the air seal.

Many cans (perhaps 12) could be placed in the "half" tail shaft ,
vacuum applied then brought into range of a set of very sharp very
fast spinning knives

Not sure how to do the spinning knives bit but I think the drive shaft
with vacuum assist would hold them secure.
--=20
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