Saw two 14 cm by 14 cm pieces out of the wooden board.
Saw four 14 cm by 4 cm pieces out of the wood. Saw a 45 degree corner off the short side of each piece. Glue these pieces together on top of a 14 cm by 14 cm to create a box, leaving the top aside for the moment.
Drill a 6 mm hole in the middle of the front and the back of the box.
Draw a cross on the remaining 14 cm by 14 cm piece (the top) and make a mark 4 cm from each corner. Drill a 3 mm hole in each mark, and drill a 6 mm hole 3 mm deep on top of that.
For stability of the base I glued some iron bars inside the box.