Maybe pressed inside a bucket or trough. On the outside it would probably crack as it shrinks. You might be able to pull a bucket out at just the right time but it would not be easy to avoid breaking the soft papercrete.
I may never return to hypertufa!!! LOL Once garden walls are in place and stepping stones, I hope to make a variety of large pots and troughs for planting outside (my home is literally on a rock). I hope that I can also, with the right mixture/texture, be able to press it around the outside of an old plastic bucket or trough and turn it into something new and interesting.
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