Hypertufa molds can be almost anything, literally. I've used plastic containers from the thrift store, the recycle, or even simply a plastic bag draped over a pile of sand.
Here are some that I've saved up from various sources; I like the square shape with rounded corner types for a pot that is simple and classic.
This one is an ice cream container, made of firm but flexible plastic.
They are smooth enough inside for the finished pot to slide out of, if it's prepared properly with a thin piece of poly film or some kind of form release product like Pam (yes, the kind you use for spraying on baking dishes!)
I reuse them many times before they go back to the recycle bin.
The mold is lined with thin poly, molded to the corners, then the bottom is filled with hypertufa mix.
The height of the sides is variable, but the higher you get, the more chance there is of it collapsing.
Dried and cured, the pot is ready to plant. There is a drain hole in the bottom, which is essential if the plants are to be healthy.
Different thicknesses of poly film make different depths of creases, which gives it a great texture.
This size of pot is perfect for special succulents, geraniums or herbs.
So next time you're thinking of going all in on a hypertufa project, check the recycling bin first. There are so many things that you can use as a mold for this fascinating material.