For our Oline, (coordinated) feet are an essential part of what we ask them to do on any given down. To help develop their coordination and spacing, we encorporate speed ladder work in pre-practice. Typical speed ladders don't work because of the narrow rungs typically employed, therefore we have to build our own.
This weekend after spending a frustrating week using the old speed ladder, I constructed this Oline speed ladder out of PVC pipe (because I am not a welder). Everything cost less than $10 to construct and was much easier to build than I expected.
36" wide and 14" deep, affording the lineman ample room to maintain a balanced football stance vertically or horizontally.
My engineering is about as brilliant as Christopher Columbus' cartography, though.....I made it half as long as I thought it would be. The beauty is, we can continue to add more rungs to this piece in the future without any modifications (will need to double the length).