This is how it's done:
First paint 17 craft blocks with white wood stain.
For the base plate, glue 7 blocks together on the long, narrow side using handicraft glue.
Apply glue to a further 10 blocks (on the long, narrow side) and stick them upright on the base plate. Make sure that you always have the same spacing.
Once dry, you can now decorate your coaster as you wish.