Above is an OpenSCAD drawing of a fluidic half adder. It works by fluid interaction within the chamber of streams entering the top two channels.

If either stream is on and not both, then that stream travels around the central cup and exits out the XOR output in the bottom center. If both streams are on then they collide and redirect each other into the cup and exit out the AND output diagonal at the bottom. And of course if both streams are off then neither output is on. The XOR output is the sum of the two input channels and the AND output is the carry out.

I am currently printing this device with a 15mm cross sectional diameter chamber in translucent orange PLA from ColorFabb. We will soon see how well it works.