I enjoy using golfing umbrellas because they're great at preventing people from getting wet. I actually made a few friends walking around with my umbrella, offering to cover other people when they would otherwise get soaked.
The downside of golf umbrellas are that they can slide down when propped up very easily.
I created this tip which fits over the end of the umbrella. The umbrella can then rotate while the bottom remains flat with the surface of the floor. Though the print works well as is, it works even better if you add some kind of non-slipping surface to the base like rubber.
Dimensions approximately: 76 mm x 76 mm x 76 mm. Scale up according to your needs.