Separating mixtures of immiscible liquids is a critical process in flow chemistry. Andrew Harvie, Jack Herrington, and John deMello have written a paper detailing how to make a useful piece of equipment to separate immiscible liquids for just $125. The project makes use of 3D Printing, a drilled out block of aluminum, a positional servo motor, some off the shelf knick-knacks, and an Teensy 3.2 micro-controller
The supplementary information contains a parts list, diagrams of parts, and some pictures that may help with assembly. It also contains a link to the project GitHub where one can find STL files and micro-controller firmware.