Weekend Carpentry: Wall Shelf
Update Aug 2014
Sketchup file at https://www.dropbox.com/s/0qa79linxceagwr/shelf.skp
PDF file at https://www.dropbox.com/s/5iaalnhmfmkkke8/Shelf.pdf
If you like to give it a try, here's the plan.
The top two are the vertical and horizontal center pieces. The last four pieces are for top, bottom, left, and right dividers. The joints are simply half lap joints (see http://jawoodworking.com/wp-content/uploads/2008/09/half-lap-joint.jpg).
Just remember to finish wood pieces before assembling. It's much easier than having to apply finish to the assembled product, which unfortunately is what I did.