Mix 2 parts cornstarch with 1 part water
Add water slowly while stirring until the mixture becomes thick and gooey
Stir until there are no dry clumps
Adjust with small amounts of cornstarch if too runny
Adjust with small amounts of water if too stiff
Use a bowl or tray for easy handling
Test by pressing quickly and slowly to feel the difference in resistance
Clean up with warm water and soap after use