Home Gunsmith forum user rhmc24 took parts from a 12 gauge shotgun and a 1857 Remington revolver and created a shotgun with a revolving cycle:
Using chambers cut off 12 ga. scrap barrels and a new $10 bbl for an Italian auto shotgun, the only other gun part is a scrapped hammer from a 1857 Remington perc revolver. Loads like a SAA Colt but underlever rotates and cocks it. Blow-by is negligible, hardly noticeable with normal shirt sleeve.
Opened for some still shots, at top of the inside pix screwed in is the firing pin, impact type with return spring. The ratchet or star with the hand is visible below on the left side, also the pawl that cocks the hammer. The cylinder indexing lock is external, operated by the under lever. At very bottom the small knob releases the cylinder to turn clockwise for loading.
Due to limited equipment I was unable to copy existing mechanisms so it is pretty much designed from scratch, largely by cut and try, trial and error, etc.
There are two more detailed pictures at the link.
Link via Everyday, No Days Off
I'd be very surprised if someone wasn't manufacturing the Winchester 1887 right now. It's a lever action 12 gauge designed by John Browning.
We love the gadgetry, creativity, and inventiveness of firearms, but we also hate milk jugs. And steel plates. And tin cans. And paper silhouettes. And zombies.