There are many different recipes for hypertufa on the internet.
Each individual works with a recipe that turns out for his or her own needs. The recipes are nearly the same but , as one person wants a "light" recipe and another wants a "heavy" one, you need to experiment to find what suits you. And I mean that heavy/light in both weight and in winter survival.
Here in Ohio, zone 5, I need my hypertufa planters to be frost hardy. I want it to survive winter after winter, without cracking, whether it goes to zero or 20 below. ( Not to mention my precious plants inside the planter!)
It needs to be mentioned that a wet/frozen planter is not going to survive as well as a dry/frozen planter. So don't situate your planter under an overhang where it will be drenched in each winter rain. Move it ! And put it upon a pedestal of bricks or rings so that it is not left sitting on the wet ground..... or horror! ...in a puddle.
The final ingredient is water and that is subject to your humidity etc. Add it slowly such as half gallon of water ( when you are using a gallon container as your part), then keep stirring and mixing, and adding a little at a time while you observe your mixture.
You can use a short handled garden hoe, or a trowel, or your gloved hands.
You will be mushing this around like making a meat loaf or brownies etc.
If you have any problem getting these supplies, here is a source.
I use a gallon plastic pitcher as my measuring unit most of the time. So using the ratio , I fill it once for the portland cement, one and a half times for the peat , then again for the perlite.
It is the ratio you use for any measuring unit: 1 to 1½ to 1½.
Portland cement to perlite to peat moss
If you are using a pint container, then fill it once for Portland cement, and one and a half times each for both the peat and the perlite.
So using this gallon as my "part", if I were doubling the above recipe, then use 2 containers Portland, and 3 containers of both the peat and perlite.
You're getting the same ratio either way.
Once it is mixed, leave it to set and absorb for a short time, such as five minutes.
When you come back after 5 minutes, mix again and add a little water if you think it needs it.
Rule of thumb is when you pick up a handful and squeeze, only a few drops should squeeze out between your fingers. But you do need to see those
drops. Too dry and you will have a hard time molding it.