Fruit Fly Trap with Oscillating Exterminating Orb

Fruit flies! A bit of fruit goes soft and suddenly you have a flurry of the annoying things around. They seem to show up summer thru' autumn when more fresh fruit and veg is suddenly in your house. There are many traps you can find on Thingiverse. Invariably they trap the little critters, but they collect and survive inside the trap. I wanted an easy way to finish them off.

My idea was - how about a trap that designs extermination in from the start? This little container has an opening to capture them (put a tiny bit of moist, ripe fruit inside). There is a little shelf inside to hold a standard 14mm marble. Dislodged from the shelf, the marble crushes the critters. Since the interior space is formed to fit the marble's curvature - there is no escape when you shake it.

Occasionally give the container a shake, and the marble slides up and down inside the container, squishing its residents. Easily tip to return the murderous marble to its holding space.

With a quick try ne