Now you "sew" the walnut at this side with the two holes together. Take some inches of the elastic braid ant turn it with the needle three or four times with som tension around through the two holes.Then fix the elastic braid with a knot. Now you can open the walnut wit some tension and if you let it loose both parts get closed together.
Through the other hole you press a part of the wooden toothstick and fix it at one side with a small drop of wood glue. After some minutes you can cut of the rest of the toothstick from both sides of the walnut so only a very small part is left and works as a lock.