u/Herbert-The-Pervert-

I’m looking to cast concrete segments that stack together (like lego pieces) for a project. I made this silicone mold, which came out great, but after experimenting with quickcrete from my hardware store i’m realizing that it doesn’t hold up great on the edges, and doesn’t have a smooth finish. I’m looking for concrete recommendations that will cast nicely and wont chip or break on edges or walls. the walls near the bottom are 1/2 inch thick. any recommendations or suggestions would be super appreciated.