First step is to make the mold, by folding the paper into a pipe, using the method showing above. I choose the cardboard as the material, seems like it is strong enough in this size. My first try failed, as you can see in the right picture above, because the concrete won’t go through, not even a little bit. I think there are two reasons: not enough water and the paper pipe is too thin.
So in my second test. I adjusted the recipe, doubled the amount of water, so the mix turned out to be liquid like. And also, I re-folded the paper to make it less in height, but much more wide opened. This time, after adding the concrete, I can see it was going down slowly and then it stopped at some point. I guess it was turning into solid there.
In the result, you can see the concrete stopped approximately half way and due to this the cast also broke down from the middle.