One can cut one from tool steel on a mill with an indexing table, or maybe broach it with the right cutter. 
Hell even filing it by hand out of 6061 bar might work, those bolts are not in there that hard(at least from the factory they’re not) If someone rebuilt and put them in at german torque spec then fowgetabootit :lol
Did you order one from that site? cost? I used to have a triple tool set that had three sockets, with the male one having three different inserts of varying lengths.