Concrete numbers (molds for casting) 0-8

thingiverse

A set of 3d printed molds for casting your own concrete numbers (0-8). I made these for my wedding to use as table numbers, they looked great finished with some 'upcycling' spray paint - one side silver one gold. I didn't make a 9 or an 8, but 8 is included (untested). Zero because I'm a code nerd :) Some top heavy numbers need a base plate: 8mm flat bar in my case, cut and polished. I used an M10 wingnut embedded in the concrete casting, and a very short countersunk bolt in the plate (see pics). Most of the numbers are made from 2 part molds that are glued together (I used hot-glue and it held fine). For each number: - glue the 2 halves of the mold, sealing any leaks. - make the mixture (adding water to pre-mixed concrete) - scoop the mixture into the mold - get the mixture into the corners (I used a metal ruler) - vibrate the mold to get the air bubbles to rise out. I vibrated the surface the mold was on, to not crack the mold. Using a bent bolt in a drill chuck works great. The molds are quite fragile but print fast. I optimised them for my own setup: making them thin (2 walls) for my 0.6mm nozzle, with 0.25-0.3mm layer height. My 3d printer platform is about 28cm x 14cm so all the molds fit into that envelope. The moulds are a little fragile at their size, and some cracked as the concrete dried. I salvaged the numbers by sanding them. The numbers will probably not release out of the mold - I had to use heat to get the PLA soft and literally peel it away from the concrete (the middle of the 4 is particularly tricky!). I used a gas powered soldering iron without the tip, just the open flame. All in, I made about 10 numbers (2 failed) - used about 12-14kg of ready mixed concrete, so just over half a 20kg bag. It's a challenging project but well worth it! The numbers are very strong as long as your mixture is right, none broke for me. They looked great in situ and were a great talking point! :-)