Comment by jijijijij

I doubt the diaphragm which actually touches the body, or the flexible tubing of expensive scopes can be sterilized in an autoclave. This diaphragm here is cut from cheap plastic and easily replaceable, the tubing is silicone. I do not believe the flexible tubing on the expensive ones is usually silicone and replacement diaphragms probably cost as much as this whole DIY scope. Metal is resistant to heat, but porous still, so disinfecting with alcohol isn't enough, if you got nasty on it. Never in my life have I seen any doctor pulling a stethoscope from a sterile paper bag. It's likely not as clean as you want it to be.

I believe, in practice you should avoid putting it directly onto the heart, keep a layer of healthy skin in-between. Given the scope of the scope, that may be acceptable, considering the alternative may be direct skin2skin contact with your patient...

But yeah, generally, 3D printed objects are not easy to sanitize properly.Eg. their porosity makes them not safe for repeated food contact. I mean, the glass transition temperature of ABS is 105°, so you could dip it in boiling water, but that's not enough for making it sterile and consequent water inclusions are a welcoming place to start a new family a few hours later for any remaining spores. You could try fractional pasteurization and heat drying, in a pinch, at the end of times.