Very quick print.

Parts

1. Plastic tubing with an internal diameter of 5MM, cut into lengths of
   1. 16cm x2 
   2. 30cm (or longer as you prefer)
2. Balloon, top cut off
3. Silicone ear protectors from an old set of in-ear headphones

Printing Instructions

• Infill doesn't really matter, most pieces will be only perimeters, and the body has an explicitly empty chamber to allow air transmission
• Brim for everything except stethoscope_body
• No supports
• ≤ .25mm layers
• PLA or PETG

Assembly

1. Print all parts, including 2 earpieces
2. Push a 16cm tubing length through each of the guides, straight part first, until 5mm or so extends out from the guide.  You may have to push hard.
3. Press the silicone ear protectors on to the earpieces
4. Push the earpieces into the tubes
5. Stretch the bottom of the balloon over the bottom of the bell.  Try to get the balloon taut, so that no wrinkles are visible
6. Connect the tubes to the body and bell
7. Listen to your heart