A Capital Puzzle
Take two thin pieces of wood, of the size shown by the square. With your fretwork saw, cut out, from one of them, the X-shaped pattern, and glue the piece surrounding the X to the untouched square. Then, get four tiny ball-bearing the X to the untouched square. Then, get four tiny ball-bearing balls from the nearest cycle shop. They should be less in diameter the thickness of the wood.
Countersink a shallow depression at the centre of each of the four circles. Drop the four balls in the channels, add a square of glass to fit over the wood and bind up the edges with pass-partout strips. You now have an admirable puzzle. The game is to get all the four balls, at the same time, in the depression within the small circles.