After a rough start when my MDF beadboard flew off the roof of my car in a huge gust of wind and tore in half... and the lumber yard not selling 1x3's so I had to use a 1x4 for the header.... my boys were really excited to see their new bookshelf this morning. I omitted the bun feet for now, and elected not to do a cutout on the header.
The MDF I used is 1/4 inch beadboard because my local lumber store didn't have 1/4 inch plywood in stock. I love how it looks, and it didn't add a lot of weight. The price was comparable to 1/4 inch plywood too. But it did tear and luckily one of the pieces was long enough to use as the backing. Barely.
Except for the footer pieces and backing which were nailed on, the whole thing was built with my new Kreg jig! :-)