I had a new, unconfigured laptop which provided an easy opportunity to participate, since I could just wipe it clean afterwards. I set it up fresh with Windows 10 a few days ago and made sure it was fully patched. I kept the machine offline when I wasn't using it, and more recently I downloaded the Rust implementation of powersoftau, which I compiled using Visual Studio Code w/ Rust rls (which also required I install Visual Studio C++ desktop tools).
When it came to the ceremony, I kept the machine in my sight the whole time and no other human beings were nearby. For entropy, I simply mashed my keyboard... a lot (much longer than I felt was necessary). Upon completion, I fully wiped the drive with DBAN (currently in progress).
Here's my BLAKE2b hash:
7573a747 d9b4e480 00de2715 c5bfa2ff
1c515371 4608cea3 97fae0fe 72846297
3a5b4d87 ce3e2a78 61d95a1e 59e723f9
6af41c1c f1b915ae 5ad5730d 1ccbaa91
I also posted it on Reddit: https://www.reddit.com/r/zec/comments/7v0889/50_participants_now_for_powers_of_tau_its_not_too/duo4808/