here is a fun sequence of pictures
color in some steel with sharpie marker, scribe a couple lines, prick punch the hole center
scribe some circley dealies with a small divider
wow awesome circles
center punch the prick punched mark then drill
nice straight hack saw cut, a breeze to clean up with the file
file the radius for a clean looking tab
okay i left a few steps out-- filing notches in the tubes and shaping the end of the tab that fits into the tube, and brazing them in.
fun stuff, eh?