DIY, master square cylinder
Channel: K Kim FinaxMusic
Date: 2018-12-12

many thanks for great explanation at links below;

https://www.youtube.com/watch?v=m4mH120Lf68
https://www.youtube.com/watch?v=aFBZFComFQc

base material from a surplus ground cylinder(carbon steel) directly from a small ground cylinder factory.