I bought the sheet metal pocket kit (they call it a shelf) from George & Becki Orndorff at
http://www.fly-gbi.com. There is one for each side between the two bulkheads/formers forward of the seat. They are dirt simple and I just set them asside when they came with the upholstery material. After flying a few cross country trips and diging charts out of my flight bag under my legs I said there has to be a better way. I wondered about the "shelfs" which are open top sheetmetal pockets with an approx. 1" opening at the top and maybe 3" deep. I cut, bent and installed them with sheetmetal screws. They are GREAT! I upholstered mine but that's your option.
Bob Axsom