Use a mitre box and saw to cut 54 x 9cm lengths of 30 x 18mm dressed pine. (If using timber of another dimension, be sure to cut lengths that are three times the width of the timber.)
Sand all edges of each 9cm block with light sandpaper.
Use colour samples pots to paint the blocks, 9 of each in 6 different colours on all surfaces.
Allow to dry and you’re ready to stack and play.