We had provided some weed block or if you don't have it a piece of paper to act as a barrier to hold the plaster lay that into the form and tape it with tape. We want the plaster (#1 Pottery) to breath.

For each 10 pounds of plaster you want to mix add seven pounds of water take a small amount of the nylon fiber and disperse it in the water.
Then add the plaster to the water allow it to slake for 1 minute then mix vigorously with a drill mixer preferably.

Mix as much plaster as you can in a 5 gallon bucket (20 lbs?) and pour into the form. working quickly mix up all the plaster and keep layering it in until the wedging table is full.