I printed philthyfool's design, and it's nice, but the cap kept dropping out of it. I wanted a screw thread for positive retention, so I re-built it in Fusion 360, and added a screw thread (45mm outside diameter, 41mm inside diameter, 7mm pitch, if you're interested)
Printed in PETG at .28mm on an Ender 5 Pro. Used 20% infill. Printed it flat on the visible big face. Used lines support, no interface or roof, support everywhere. Got a pretty clean print out of it.
Before you take your gas door screw out, might want to have a spare handy. I destroyed my original screw, had to booger it up to remove it (vice-grips to turn the screw head eventually worked). Those Philips #3 flutes are really soft metal and strip right out. The screw may have loctite on it or something. Anyway, I needed to order another screw from the dealer, who didn't have it in stock.
The author remixed this model.