The wing knobs and T-bolts from the last post were working well for the cam clamps, but one thing I thought would make them better is if I could install and remove them without having to slide them down and off the end of the track.  There are special nuts for aluminum extrusion track that can be dropped-in and twisted 90 degrees to engage the underside of the track.    As Splinter mentioned, they can be expensive unless you get them on Amazon and with metric sizing.  So, I got a bag of 50 with M6 threads.  Sorry 1/4-20, we had a good run. 

I remembered that I had a scrap of roughly 3/8" plywood in the garage that came from a Lumber Liquidators pallet.  It was not quality plywood, but it would work for knobs.  The knobs needed M6 threads too, and I thought that the rectangular track nuts would actually be ideal since there would be no chance of cam-out like there would be with a hex nut.   I created a recess in both the knob and the 1/8" plywood disc standoff to capture the nut, leaving the square center "chimney" of the nut flush with the outer surface.

I cannibalized an M6 by cutting off its head.  It became a T-bolt with one of the new T-nuts threaded to one end (which will be permanent as soon as I can track down my threadlock).

Then it can be dropped-in anywhere along the track.

Turning the knob rotates the nut which locks in place as the knob it tightened fully.

With the prototype done, I setup to cut 30 knobs.  Eight of them disintegrated while being cut because some of the plies were not glued.  But 22 knobs ought to be enough for a little while.  Check out the edges of that plywood.  Definitely not cabinet grade!  Knob grade?  Yep.

After assembly and glue-up, I wicked some low-viscosity CA glue into the edges of the plywood, hoping that would help anchor any loose plies.

I've got some M6 threaded rod on order so I can make a set of T-bolts to outfit my current set of clamps.