Bogen 3299 Quick Release adapter and plate $28 @ B&H
I found the two knobs with 1/4-20 thread/bolt in a hardware store. If people are interested
I could try to get the manufacturer name and model number. Cost $3.50 each.
1" x 1/4" aluminum bar, bent in a vise.
Piece of aluminum right angle stock. Used angle stock instead of a flat plate for more rigidity.
Slot made by drilling and filing. This piece and slot turned out to be longer than needed
for the offsets required by my Tokina ATX242 zoom lens. If I was going to do it again, I
would have made it a bit shorter and would have put the slot and pivot hole a bit closer
to the edge to give the knobs more clearance.
Note how I had to rough up the parts of the L bracket and horizonal piece where they meet.
The original finish was so smooth that even with the front knob very tight, the weight of
the camera would make the horizontal bar move.
Tools used: electric drill w 1/4" bit, hacksaw, small round file, flat file, vise.