The eNable Chapter at UMass Lowell recently printed two hands for Emily, a young recipient from Germany. The eNable Community Foundation is an international volunteer organization that uses 3D printing to solve problems for children with limb differences. In addition to her two hands, Emily and her family wanted our group to look into creating a device that would help her swim. The result of this design effort was the Swim Fin. The fin is attached to the recipient’s arm using flexible tubing. The paddles on either side of the main body fold down when the arm is brought forward through the water on the upstroke. When the swimmer pulls the fin through the water on the downstroke, the paddles flare out and are held in place by the cross brace. Here is a video of the Swim fin in action. The Swim Fin has four printed parts, two M5 socket head cap screws, two hex nuts and two pieces of 1.75mm filament. A #10 screw can be used if necessary. The Swim Fin was designed in SolidWorks, and printed on a Folgertech Prusa i3 2020.  The Swim Fin was easily printed, and assembled. Here is an Instructables detailing how to make the filament hinges. Thanks to BarbMakesThings for the instructions that inspired the filament hinge. A full design history file can be found here, which outlines the design decisions for each revision of the Swim Fin. The released STLs are dimensioned for Emily, if a larger size is needed, here is a link to a zipped folder with the STLs, STEP files and the original Solidworks Documents. If you have any questions about the Swim Fin, or about eNable Lowell in general, feel free to contact us at [email protected]