For review: http://en.wikipedia.org/wiki/Contact_angle http://en.wikipedia.org/wiki/Sessile_drop_technique This is an apparatus for a goniometer to measure a liquid contact angle using the sessile drop methodology. As with my USB microscope stand project, you need a USB microscope, 1/4"-20 thread rod and nut, and M3 screws, and some superglue. The sample stage is optimized for a microscope slide. Version 2 is shown since I am still printing version 3. Please note that shapes.scad file is needed to view the microscope stage 1 of 2 OpenScad file.Assemble as shown. Superglue top knob and nut in the microscope slide stage. You can adjust the back clamp to make the USB microscope sit snugly in the base. The slot behind the microscope slide is meant for colored card stock to get the best optical image of the drop sitting on the sample surface.