This puzzle is the complement to the puzzle from 1 to 5 on the different representations of numbers.

First, engrave the front side without the circles.
When finished, remove the pieces but leave the frame in exactly the same place.
Then engrave only the circles.
Remove all the wood and put another board for the back
Engrave the back.
Glue the frame of the front part on the back board. Be careful while spreading the glue as somes parts are very thin.