Make this X Bookshelf! Free step by step plans from Ana-White.com
One sheet of 3/4" plywood ripped into strips 15 1/2" wide (you only need a little more than a half sheet but will need to buy a full sheet to get the cuts)
8 - 2x2 @ 8 feet long (may not need this many but added extra because of the angle cuts)
5 - 2x4 @ 8 feet long
4 - 2x4 @ 72"
10 - 2x2 @ 27 1/2"
5 - 3/4" plywood @ 15 1/2" x 27 1/2" wide
6 - 2x4 @ 15 1/2"
4 - 2x2 @ 15 1/2"
4 - 2x2 @ 33 1/8" (CUT TO FIT!!! both ends cut at 25 degrees off square)
8 - 2x2 @ 16 1/2" (CUT TO FIT!!! longest point measurement, one end cut at 25 degrees off square, other at 40 degrees off square - see diagrams)
Please read through the entire plan and all comments before beginning this project. It is also advisable to review the Getting Started Section. Take all necessary precautions to build safely and smartly. Work on a clean level surface, free of imperfections or debris. Always use straight boards. Check for square after each step. Always predrill holes before attaching with screws. Use glue with finish nails for a stronger hold. Wipe excess glue off bare wood for stained projects, as dried glue will not take stain. Be safe, have fun, and ask for help if you need it. Good luck!
The best way to get your Xs just perfect is to take a 2x2 and hold it over where it will go. Mark the angle cuts and then cut with a jigsaw. These guys can be attached with pocket holes (1 1/2" and 2 1/2" pocket hole screws) or can be attached from top and bottom with 2 1/2" wood screws predrilled. Also attach to the middle shelves with screws or nails.