I built boxes out of OSB and glued/stapled them together. I then put a 1x3 nailed on each side of the opening between the trusses. Slip the OSB box in on top of the 1x3's.
Each OSB box also has some 2" wide OSB nailed inside to act as shelf supports. I then cut some 3/4" OSB to be shelves. I can add or remove shelves as needed.
I then OSB's the side walls in the attic.
Seems to work well, supports a lot of weight. I made 16 of the boxes for my 48' long shop. 8 boxes on each side.
