How to Make Concrete Molds for Cinder Blocks

Decide how big you want your cinder blocks to be, and buy some wood at a home-improvement store. For example, if you want 4-inch-long, 2-inch-thick and 2-inch-high blocks, you will need 2-inch-wide material. Alternatively, 4-inch blocks require 4-inch-wide material. Any type of wood will do. Purchase wood screws that are long enough to go through whatever thickness of wood you purchase.

Mark the pieces of wood according to your cinder-block dimensions. Use a tape measure and pencil to mark your pieces accordingly. Cut the pieces of wood down to size, using a miter saw. Assemble the frame by screwing the pieces together so that you have a box frame. Also screw a bottom onto the box, using a piece of scrap wood.

Fill the form with concrete, and allow it to rest for at least 72 hours. Unscrew the bottom of the form, and gently tap the sides of the mold with a hammer to break the bond between the cement and the mold. The mold will slip off the block, leaving behind a custom cinder block. Create as many molds as you want, and reuse them to create more cinder blocks.