Yes I think that by using the library functions you should simplify your life. The goal is to create a function that does the machining and to put it in the library to reuse it.
and if I want to push the thing even further and tell him to add the 1/4 gas cap in the body in the library function... is it possible I just tried it doesn't work
otherwise you can create a block and bring it back to the sketch and do a removal of material by revolution whenever you need it; you will of course have to divide your sketch into 2 in relation to your desired result...
But as usual I write and validate my answer 20 minutes later so inevitably it was bound to happen I delete my previous post . May the force be with you