Original umbrella holder was silver in color and very slippery so I made new with FreeCAD & Prusa Mini+ with black PETG.
This was my first FreeCAD design. (jihuu!) The disk bottom and walls are 2mm thick, maybe 1mm could've been enough, but I wanted to be sure, that it's water tight and won't leak to my wooden floor. 
Disk measures:
hole = 4 cm
diameter = 13 cm
Surrounding walls = 1 cm
thickness = 2 mm