Order these parts and place the round cap on the long bolts and the star caps on the short bolts. Use red locktite to secure the caps to the bolts and enjoy the simplicity of taking them off when you need to.
McMaster-Carr.com
93210A017 METRIC BLACK−OXIDE FINISH STEEL SETUP STUD,
ROUND SHANK, M6 SIZE, 65MM LENGTH, 1MM PITCH 2 0 6.76
EA 2 EA 3.38
60765K332 METRIC STEEL KNURLED RIM KNOB, M6 X 1
THREADED HOLE, 25 MM DIAMETER 0 5.90
EA 2 EA 2.95
6390K52 METRIC PHENOLIC FOUR−ARM KNOB, M6 X 1
THREADED STUD, 32MM DIA, 30 MM STUD LENGTH
EA 6 EA 1.92
Quad B in Vicksburg, MS