Tomorrow I'll post my solution for rack tabs in my thread tps://www.bikeforums.net/framebuilders/1158438-rack-making.html . I've taken off my walking boot and the camera in downstairs still.

As mentioned rack tab can be installed much like tabbed drop outs are. Actually they're easier as both the stresses and the gaps to be filled are less. I have a few different tabs, much like what has been shown. But I wanted a different strut/tab arrangement so the tabs are also different then what's available. I'm using 5/16" tubes and a center bracket to the brake bolt because the rack will see only very light weight.

Those Llewellyn bits look interesting but using a M3 bolt??? They also are to direct mount to that very popular brake, Pauls.

As to using a piece of tubing as the tab, sure it will work fine. Bolt length isn't a problem as long as the bolt is seated well on the tube/tab and the tube/tab is seated against the eyelet solidly.

Will you add light tabs? How about pannier lower hook points? Andy