To make pots with concrete, two disposable pots ( like the ones plants come in at the nursery) or bowls each in two different sizes will be used. Coat the inside of the pot or larger bowl with petroleum jelly. Mix the concrete to the consistency of peanut butter and add a small amount of concrete to the bottom of the larger pot or bowl. Place the smaller pot or bowl (coated with petroleum jelly for easy removal) inside the larger one, then fill in with concrete around the smaller pot or bowl using a trowel. Once the concrete dries, remove the smaller pot or bowl, then turn it upside down and carefully remove the larger one. I hope this helps!
Are you talking about Hypertufa, lots of videos on YouTube.... https://www.youtube.com/results?search_query=how+to+make+hypertufa+pots
Hi Wendy: Here are a couple of sites that may help:
Hope this helps and good luck