I made my carts with the wide mesh drawers:
http://www.containerstore.com/shop/e...014211&N=80348. The drawers are 20" wide. The BSP dies fit it it with plenty of room to spare.
You can purchase the carts from the Container Store with all of the components already bundled together in a box. That cart has the medium width drawers. It's identical to what I did except the drawers are 16" wide instead of 20". The BSP dies are 12 x 12, so they would easily fit in the 'regular' cart.