Multi use Ends cap

I am not sure what I should call this, it could be as small as a 8mm Z-Rod cover (as default), a pencil cap, a nail cap, a hammer head cover or even toothpick saver :-) (you don't want that). But if its diameter is large enough (with base optional), it could become your pet's food tray, a nut/bolt tray, a water cup, an emergency flower vase. It's a customizer thing, so play with the numbers to see what this can bring you, be creative.
Enjoy.

Update 1: add version 1 with the base not shifted down too much (only see if the base height is less than thickness)