Here's a clip showing the piggies vertical hay rack setup. Poof and Truffle can be seen yanking out strands of hay from the ground level while Belka climbs to reach choice strands higher up. After investigating the camera, Peaches joins in on the munching.
The hay rack itself is made from C&C grids, lined with a coroplast backing and secured to the cage walls with a large binder clip (for a closer look, see earlier post here). Bricks placed at the sides wear down their nails and allow them to reach hay at the top. Meanwhile, an extra layer of fleece and towels layered underneath the entire setup makes cage cleaning easier.