I simply have too much work at the moment to dig into all those Penn Dixie finds, but I did manage to play with one roller yesterday morning.
On the far left, this is how I found it, barely peeking through the shale. I had a feeling it was complete, so I put it in the bucket. The next image is what it looks like after a bit of work with the Dremel and dental picks. On the far right is after using a small flathead lens screwdriver. The purpose here is to eventually free it from the matrix, but trenching around it is a good idea to avoid accidentally causing a crack to run through the specimen.
Using sturdy tongue and groove pliers, I was able to clip off the matrix to free the bug. Not a bad looking one, although it is more crushed than enrolled. There's also a tricky bit of "underbite" where the pygidium protrudes farther than the cephalon. On the right is what it looks like after some sewing needles and 20 minutes of air abrasion at 40 PSI using baking soda. It still has some stubborn matrix to remove, but that may have to wait until I can get my hands on some dolomite as blasting media. Still, not a bad job compared to what it initially looked like!