The image to the left is a pile of rods suspended from the ceiling by a 1/4" x 1/2" screw. These rods were suspended for more than a month until they were needed for our experiments. If you look closely, you'll see the two narrow lines at the top of the image, those two lines are from the string connected to the screw. The screw is much harder to see, but is located at the bottom of the pile.
We formed this stable pile by first pouring acrylic rods (3" long, 1/16" in diameter) into a big cylinder. Next we pulled on a screw at the bottom of the pile until all the rods were outside the cylinder. The pile is able to remain rigid once the side walls of the big cylinder is no longer present for large aspect ratio (> 35) because particle entanglement is enough to greatly constrain the ability of particles to rotate.