We’re accustomed to covering the use of 3D printing in casting, usually as a lost-PLA former in metal casting. That’s not the only use of the technique though, and perhaps one of the si…
Having tried similar things, I cannot stress enough how much you want to be printing molds like this in TPU unless you really really want your mold to be permanently embedded in the concrete
@RegalPotoo@Wilshire good point. Release agents are used for casting concrete. They look to be oil and water mix so I'm guessing most plastics would be compatible.
Also has to be a clear path out for the print/concrete.