To make the ring I took two big MDF boards and made another makeshift drawing compass, with a radius of 25 cm. I put the two boards next to each other forming a square 1mx1m. Using diagonals I measured and found the centre of the square and started drawing the inside hole of the ring with a diameter of 50cm. I then proceeded with the outside, making another Drawing compass with a radius of 50cm and drew a circle matching exactly the size of the two boards and fitting perfectly inside.
I then proceeded to cut the ring out of the boards with a saw. I ended up with two separate half circle pieces, that would cover the top of our installation.
Project Fat 