I created this to go between the hummingbird feeder and the house to stop ants from drinking the sugar water. You fill the base with water and the ant will not cross it. I printed it on a Makerbot upside-down with supports to give a very clean external surface. I used Solidworks with a "spline" that was revolved around an axis. Then the "shell" feature to give it the right thickness. It took all of 5 minutes to design it.Print it upside-down (bowl faced down) with supports. This gives a great external surface finish. I also use 50% fill to make it watertight.