I built this ring roller a couple years ago. I needed a way to take narrow( 3″ or less) flat stock and make a ring for making flue pipe adapters for my wood sauna stoves that I build. I could have gotten chunks of DOM tubing or pipe from the metal store, but I didn’t have a way to make a straight cut of something that large, also, paying for cuts from the supplier is expensive.
I tried a Harbor Freight Tools ring roller first but that broke during the first roll. After some searching on Pinterest and YouTube I found sub very buildable versions that I could make. a couple trips to the metal pile and eBay, and a cheap Harbor Freight Jack yielded a useable tool.
The thing that I would change is the hingepin. Under heavy loads it deforms more than I would like, but it still does what I need it to do.
The first project I made for it was a wheel to turn the roller with, it is 1″ thin wall square tubing and it was a pretty easy bend being a larger diameter
The pillow blocks are from ebay and were relatively cheap compared to what they would have cost from Grainger or somewhere like that.