Step 1: Supplies
I used a piece of scrap metal roughly A3 which is 430mm x 300mm and 3mm thick.
Some paper for rough calculations.
Pen, ruler and 90 degree set square.
Three drill bits 5mm, 8mm and 11mm in diameter (I prefer to progressively widen holes drilled in steel than go to the final diameter).
Step 2: Dimensions
I had a piece of steel lying around which looked the suitable size and did my design from there. I chose my teeth size from rough drawings and approximately divided the size into the length of my work piece. I also decided to design a rake that was easy to cut out with a hacksaw and the fact that not much natural snow falls in Southern Africa so the snow tends to be dense and icy. The sharp teeth are quite aggressive and could be rounded for use on softer snow. Also if aluminium (this by the way is also the correct spelling of the element listed as "Al" in the periodic table of the elements) is available it would make a lighter rake that wont rust. I think it would also have to be approximately 6mm thick to have the same strength as steel.
My final dimensions for the teeth were 50mm high x 40mm wide with a ~11mm drill bit used for the rounded parts. Total width of the rake is 430mm. This made 11 teeth with the two outer ones 5mm thinner than the rest.