Garage Shelving, what are people using?

[In The Ten Ring]

What I plan to do in the future:

Wood, 2x6 boards, and build my own from the ground up, made to exact dimensions, to store all my parts and tools and do so via maximizing storage space with what I have.

For the time being:

Once the truck is running, I'll sell off some gear and clear out the space a bit more, and run 14 foot 2x6's across my two widely spaced plastic shelves to maximize storage space there and allow my mower to fit between the plastic shelves and under those boards.

Why 2x6's? That's the largest size my miter saw will cut.