Tower height = max foam height + 50mm of clearance. Tower spacing (the Z dimension in machine coords) = max foam width + 30mm of clearance on each side.
Don't oversize too much — bigger spacing means a longer wire, which sags more in the middle (gravity bow), which means worse cut quality on tall blocks. 500x500x500 is a good general-purpose size; 800x600x300 is great for wings.
Don't oversize too much — bigger spacing means a longer wire, which sags more in the middle (gravity bow), which means worse cut quality on tall blocks. 500x500x500 is a good general-purpose size; 800x600x300 is great for wings.