Thank you, Millenniumfalsehood
Canons are rolled around stick of appropriate size, otherwise I was affraid they will not be straight. I did not roll it as one continuouse strip but layer after layer. Every layer is moistured and carefuly preshaped by rolling to desired shape. Slow preshaping makes smooth shape without wrincles. That way the edge has no step when joined and when gently burnished edge is not so noticeable. But I can asssure you edges are still there and visible.
It is also important to properly orient the part on the page so the rolling does not go against the paper fiber direction. It has tendency to wrinkle lots more than. Right orientation can be tested by wetting the paper. It starts to curl naturaly and you can see the right direction.