Steve, here's something invented in the slot car dawn of time that I've always liked. They reproduced the Monza or racing style quick fill gas cap like the one on this King Cobra....
....with a straight pin and slotted head screw:
The Pactra body has a big blurry wart that's supposed to represent a gas cap. Time for more mechanical detailing.
The pin is soldered in place with a good amount of solder to fill the slot and blend things together:
After some shaping and a coat of Tamiya gloss aluminum paint I have an old school gas cap to cover up the wart in the Pactra body:
OK, I'd better explain that rusty vise picture. I don't want the American Society for the Prevention of Cruelty to Cheap Miniature Drill Press Vises (ASPCCMDPV) knocking on my door.
I have 2 of them. One I solder on, the other one I don't. I know after soldering I could wash it with soap and water or baking soda and water and blow it dry or heat it in an oven, then treat it with oils and preservatives but I don't. I just wipe the vise off and carry on with my project.
Over time my 2 vises look like this:
To show that no cheap miniature drill press vises were destroyed during my projects and prevent the wrath of the ASPCCMDPV, I spent a few minutes with a wire brush and voila!
Now it can slowly start rusting all over again and I can work on the wheel inserts.