I want to make a mold of a cement retaining wall block.

I was thinking that vacuum forming would be the best way to go, but not sure about the textured face of the block. I'm also not sure what the best material would be, something flexible enough to peel off the block for re-use, but sturdy enough to not need a form around it. Any ideas would be greatlly appreciated!

aarone8 years ago
There are a number of materials that would be fine for this. A liquid rubber latex that cures in air should do it. If you make it thick enough, it will stand up to use. You are very likely going to need a mother-mold/ supporting form for this. General rule of casting: use a hard material to cast something soft - use a soft material to cast something hard. You're casting a very hard surface. It's not going to give when you remove the mold material, which means you'll likely need force to remove it, which means that you may very well hurt the mold in the process. I would use latex, and reinforce with plaster/stone.