I’ve come across posts about using rolling pins as well. I don’t see why this couldn’t work, provided you are careful. With any new exercise, take it easy at first. See what happens.
I’ve been doing something similar. Sometimes when I’m clamping, I’ll rest my member on a table and lay a hardback book across the top and apply pressure on the book with my hands, squeezing my clamped cock between the book and the table. This does give me a greater width expansion than regular clamping. It also “flattens” the boy out some. But for me this is good, as my penis is thicker in depth than in width. I haven’t experienced any additional red spots or anything like that. But I’m careful about anything that puts pressure on the main nerve running along the top of the penis.
I don’t do this exercise regularly, and I haven’t been doing it for long. So I don’t know what kind of long-term change it will produce. But I like the immediate effect, so I will continue it.