Easy and Cheap Shelf Risers

This Easter Bank Holiday Mega-Thon as it shall be henceforth known gave the boy and I time to procure an Expedit bookshelf from the Scandinavian furniture giant that is IKEA. The shelves will easily accommodate 2 rows of books with a shelf riser for the back row:

Instead of spending heaps o' money on some kind of specially made item, I found a cheaper alternative:

Functional and it will serve as a very handy ararat should the zombie invasion strike and we make it long enough to hole ourselves up in the flat!