Designed to prevent water from hitting the end grain and direct it away from the post.

The different designs are purely for decorative preference and are both just as functional.

The end of the post needs to be a clean-cut 90 degree angle for the cap to sit properly but the caps should slip snugly on while also being possible to remove with some effort (ie, it won't wiggle or come off by accident).

I designed both post caps with a flat side on which they can be printed with no supports. This also gives it a nice consistent surface finish with less pronounced layer lines. I used 20% gyroid infill and they were very strong and chonky; you could probably get away with less.

Of course use PETG like I did or some other weather-resistant material if using outside.