Upgrade to stethoscope design as part of a class project (Advanced 3d printing - MY5777 Michigan Technological University)
Original idea was from a previous student (Brett Barker).
Improved upon the design by changing the ear piece to a diaphragm ear piece with a dual head and the capability to attach a membrane (in this case a stretched balloon) to increase the capability of the device to pick up noise.
Will need black plastic tubing (24 inches), two pieces of tygon tubing (6cm long), a small balloon, and a 2 " OD plastic O-ring. All tubing should have an outer diameter of 1/2".
For the diaphragm, cut the nozzle of the balloon off and stretch the remaining balloon across the bottom (larger part) of the earpiece. Hold in place using the O-ring.