Well never you mind.
I see there isn't much activity on this forum, and I just had go dive in without y'all.

Good luck with your projects.
I'll drop in again someday.

If there is one thing that you will learn from making hypertufa is most of what you learn is from trial and error.
Most likely no one knows how much you need ( as a result no quick reply) because all the forms are different sizes. Your post did not indicate how big the box is for your mold.
Take a coffee can and measure each ingredient. Log in in a notebook for later reference. Experience will teach you to have a smaller second mold ready for any excess. Or make small tufa balls, then flatten then and they will become feet for your containers.
Good luck, take pictures and post you results

Mike

Here is a link that might be useful: My Blog

Thanks, Mike.
My first experiment came out just fine. You can see that what I measured out did my box and then a flattish piece as well. Now I have a better idea and will move on. The two pieces in the picture have now been steel brushed and re-wrapped in black plastic and are .... curing under that table.
I realized after those pieces came out that I had used my 3/8" screen for the peat, and it is a bit chunky. I've already sieved the peat for the next project and used the 1/4". I think that will make it smoother.

Susan