I'm partial to DucaBike and made them using their plugs.
For the seat cowl look for a thread labeled "Seat Cowl Fastener Bling" dated April 4 in this forum.
The frame plug is much more complicated. I used a plug sized for the Diavel and expended several hours on a mill and lathe. The stock bolt is modified and the Duca plug was then modified to be a cover. Net effect is the same appearance as a plug.
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