We went to the store with the intent to buy this time, and this is what we ended up with :

2 wooden rods : 500m length 10mm diameter

1 steel rod : 500mm length 7mm diameter

2 wooden planks : 2500 x 10 x 15mm 

We already had the other planks ready from an earlier session on the 17th (December). Take a look at the "Intsructions" of this project for the exact measurements. The sketch of the maze was 3D printed on the 21st.