Two wooden shelves. Or use the 2x4 and particle board for another project you're working. The wood will cost much more new at Home Depot.
I built too many of these shelves for my garage (there are 2 extra shelves that I'm selling). The pic of the larger installed shelf in my garage shows you how they can easily be installed. Each of the two shelves measures 2 ft x 4 ft. In the last picture, see the shelves highlighted in green that are included. the support 2x6 lumber highlighted in red are not included.
If it's still posted, it's still available. We're located very close to where the map in this ad indicates (corner of Gum Spring Rd and Braddock Rd). When responding, please let us know what day / time you'd be able to stop by.