Anyone working on a ball check valve?

[UberDuper]

I'm not really a modder so I'll never do this but I'm amazed nobody is making / selling something like this.
A simple ball check valve like so:
Fill the cart, plug it with a check valve. Drop a spring just smaller then the inner diameter of the atty tube into the atty. The bridge actuates the ball to open the flow.
Push down on the cart like clicking a pen to get some juice.

I could also see using a tiny diaphragm pump with a push button on the cart to compress the diaphragm but that's probably more difficult to get appropriately sized parts for and would consume too much space in the cart.

Someone plz build it.

UD.