You can follow the link to a bit of a tutorial and a wiring diagram. Sorry, there's no app or UI at all, but you could ssh into the pi and run it from the command line.
It looks like wood flour, which is a pretty common additive for epoxy to make it fill gaps better.
I think I outlined the reasons in the README file of my code. I tried a couple apps that didn't really work for me (not being able to work in the background was the biggest problem) and then reasoned that I could write something that would do 99% of what I want very quickly as I'm a python developer and I was already familiar with sl4a.
So, the perfect app may already be out there, but I didn't find it. Someone later pointed me to DailyRoads Voyager, which looks to be very close.
I've loved this song since it came out, but I just realized that is Tomo on the drums. I was a huge God Street Wine fan, so it's great to see him do some more great stuff. Rock on man.