As always, a word of warning
TURN DOWN YOUR VOLUME BEFORE HITTING PLAY!
I love that I have cracked the code on using Sonic Pi to make Harsh Noise Wall.
Here is a wall that I made using the FL Studio sample. Slowed it down, and fed it through my effects chain.
It ran for close to a full hour. I had to stop it because it was getting a little repetitive at the end.
But yeah, I figured with a name like that, I would share it here with you guys. 
Fun Fact: I also sampled Sonic Pi on the Intro to my Mellow Silence Wall EP. You should check it out if you are intrigued.
Also, if anyone wants to do a harsh noise split with me, hit me up.
Edit: Here is the code
pastebin.com/sGZqXf5R