Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4777139.

A vent cap to top old 4.5" outer diameter vent pipes. This should help prevent rain from getting into the pipe. Use construction adhesive (Liquid Nails) should keep it in place, but I also added backup holes if you want to use screws to keep it in place. These are replacements for the 2 caps I lost in heavy winds.

Note, these 4.5" vent pipes are old, and possibly made with asbestos, so be careful when drilling (wear a respirator). My vents aren't even functional anymore, as the furnace and water heater they were connected to were moved / replaced. I just don't want rain getting into the roof crawl space. If you have an active flue or vent, you should use a non-combustible metal vent cap. So probably not to code.

Printed with ABS, as it's outdoors.