On the board (51cm by 51cm) the holes for the iron rods must be created. You start at 1.5 cm from the side and then a hole every 3 cm. When you're finished there are 16 holes on each side.
Then you make all 32 iron rods 50cm long. Each end of a rod has to be bend 90 degrees. Then you put the ends of the rods in the holes. When all the iron rods are in the right position, you can put a little bit of the instant adhesives between the crossings. This will make the iron robs more stable, so the blind person can feel where to put the letters.