I've been experimenting a "DIY" abrasive tube notcher to cut some seat stays/seat tube connections since I could not cut them by hand. Rudimentary aspect but happy with the final result! :
Grizzly Industrial 4" x 79" 3-Phase Abrasive Tube Notcher
Abrasive Belt Tube Notcher | Pipe & Tube Machines Ltd
Tube & Pipe Notchers | Workshop Press
DIY Tube Notcher - Kustoms by Kent
Decisive Abrasive Tube Notcher for Industrial Uses - Alibaba.com