Ledging

[JaredAI]

I use a cut off saw from harbor freight

https://m.harborfreight.com/power-tools/cut-off-saws/3-in-heavy-duty-electric-cut-off-tool-61944.html

Then a grinder to smooth everything down. But a hacksaw with a good blade and a file should do it.

[dan3]

I remember when I thought cutting a channel sounded like the worst idea. Borrow an angle grinder or find a metal shop, offer to clean the windows if they cut down some channels for you. Nice and cheap.