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! :
Abrasive tube notcher « Blog: oTm Bikes
Tooling For Pipe Notchers | Scotchman Industries
Abrasive tube notcher « Blog: oTm Bikes
Grizzly Industrial 4" x 79" 3-Phase Abrasive Tube Notcher