Bills: I used round stock aluninum. Cut to lenght you want and square it off in lathe. Drill through with a 'J" drill and tap with 8MMx1.00 from both ends. Do this in lathe to keep things in line and on center. Very easy. Run tap in with tailstock chuck. Turn chuck by hand when tapping. Use some cutting oil. Take a look a the last phot of my engine...thats how I did it! Use locktite on threads. Good Luck Capt,n