I am making the left-hand part from DuBro 4-40 turnbuckles. The hex is pretty small but if you make a tool to fit it works just fine. I loved the ones from Tom. Maybe they will be back someday. Anybody got access to a small two-spindle automatic screw machine? Couple hours setup a small pile of 1/8" hex bar stock and you could crank out about 200 an hour and have enough to supply the hobby community for a lifetime in an afternoon.
Ken
While we are at it, does anybody know where to get left hand 4-40 all-thread?