The included model is for ½" plywood but the f3d file has parameters for the plywood size which can be edited and the models will automatically adjust. Screws used for plywood and for attaching stacked shelves are #2 sheet metal screws and I would recommend ½" countersunk screws. 5 screws are used per shelf support.

No tool side peg available here Peg Accessory for Printed Desk Shelf by icybaker | Download free STL model | Printables.com