I started working on a hot end cooler that utilizes an air pump for aquariums. The particular model of pump that I am using has 4 outputs and variable strength. Instead of having one on full blast making the motor the loudest it can go to pump one outlet hard enough to cool the plastic coming out of the hot end and wasting the output of three other valves, I decided to create an adapter to take all four and connect them to one line. You could use it to combine four into one, split one into four, or really what ever you want. The interior channels are all connected so any fluid should flow from one to all and so on. I could have just bought two elbow connecters and three T connectors, for 99 cents each, but I'm a maker, and spending an hour modeling a part and another hour printing the part for a fraction of the cost is what we do. So here you go. In case for some reason you need this kind of stuff, the modeled dimensions are: 5.1mm for outside of connectors 2.9mm for inside of connectors 12.6mm between connectors 9mm for length of connectors Roughly 58mm x 30mm x 5.1mm (actual dimensions may vary by printer) Designed for Petco Air Pump model AC 9904