Geoff Roberts Framebuilding course - first and second, and third frames. And fourth (now finished). And fifth.

There's a little fixture - a V block with some prongs sticking out of it - which holds the stops in place. I eyeballed how far back to put them, and then to make sure they're level you put two steel rules on each side of the frame, touching the down tube and top tube and then check that the gap between the stop and the ruler is the same.

Tubing is Columbus Zona. You don't get a choice with Geoff. For a first frame, it's a good choice.