(Portland cement is caustic!! Protect yourself!!!)
Hypertuffa recipe: Portland cement
Elmer's wood glue
decorative junk (glass shards, marbles and metal junk)
Tools you will need:
Large mixing container
scoops (a separate one for the cement)
old shower curtain or other protective plastic cover (I used plastic sheeting I found on the roadside)
This mixture is a real trial and error process. I looked for a good recipe and found several that had the same ingredient list but some added paper pulp and others added glues (I should have). I chose to work with the basics for my first time and my pots are a bit crumbly. Paper pulp and/or a bottle of Elmer's might have helped.
Do this outdoors! Mix Portland cement 2 or 3 to 1 with peat moss, sand and vermiculite. Add water a little at a time. IMPORTANT: work in small batches at first until you get your mixture down. It should be very thick and form a firm ball when pressed into your hand.
The basic instructions are easy to find online. For these pots I lined a small container with a plastic shopping bag smoothing out any big wrinkles, packed in the mixture paying close attention to the thickness of the walls, corners, bottom and the shape of the opening. If you look up the history of hypertuffa you'll understand why you want them very thick walled--this in addition to the porous nature of the mix.
When I was happy with the shape of the pot I covered it with two more shopping bags, sealed the bags as air tight as I could get them and placed them carefully under my porch to dry. They should take 2-3 months the dry properly. Don't be tempted to peek. The longer they take to dry the stronger they will be! I was impulsive and kept checking on them and many of them came out so weak I had to scrap them.
When they are dry to touch unwrap and carefully de-mold them, peel away the plastic liner and put them back under the porch for another month. I did my project last September and did not attempt to pot them up until this July. They need to be rinsed a lot, I made a little garden of them next to a planter so I'd remember to water them as often as I watered my plants.
The biggest one pictured has a spiral of glass shards embedded in it. I waited over a year to take it out of the mold as I used a small satellite dish for the mold and a piece of one side still broke off. These do not make good birdbaths as they are very porous.
Hypertuffa is a sweet addition to the garden or to a rustic indoor decor. But this is a real trial and error process. Do a lot of research and consider your climate. I live in the desert southwest so my pots dried out quickly. Once you get it down it's really fun!