Mini Materials posted a video showing you how to make 1:24 cinderblocks (they sell a kit). Finally I can embrace my lifelong desire to have a train set, having hitherto been unable to do so due to the difficulty in accurately replicating the vast featureless Communist closed cities and rural Pennsylvania beer distributors of my imagination.
Make the tiniest cinder blocks in the world! This nine piece 1:24 scale CMU mold is the same one we use to make our blocks. Made of heavy duty silicone, these things will last forever. You can pour almost any hardening material, and they will withstand up to 500ºF
The not-obvious part here is how thin the mix is, to guarantee good, bubble-free form in the wee mold.