When working on your own garden construction projects, whether you are building a retaining wall or refinishing a patio, one of the materials that you will most commonly use is concrete blocks. You could spend your money on concrete blocks from a big box home improvement store, or you could make them yourself. Casting your own blocks is easy. All you need is concrete and a mold to cast them with.
Measure the board and make a mark every 2 feet.
Cut the board into four 2-foot pieces at the markings.
Using double-headed nails, attach the pieces into a box shape. This will be the block form. Double-headed are designed to be easier to remove than regular nails, which will make dismantling the form that much easier once the concrete sets.
Place the block form on a flat surface.
Line the block form with a plastic dry-cleaning bag. Your block form is now ready for you to pour concrete into it.