Step 2: Building the frame
Remember that you want to be able to disassembly the molding box after the concrete has set, so dont go overkill with the size of the nails. (Or, just use screws instead)
1) Start out with a peace of wood that is approx. 18 x 26 cm and drill out the six 50 mm holes using a hole saw.
2) Nail another 18 x 26 cm peace of wood to the underside of the previous one.
3) Add the 96 mm high walls to complete the jig for molding.