[ErroneousBosh]

https://www.ebay.co.uk/itm/264691582901

(if eBay kills that link, then for future HNers it's a link to an inexpensive bright yellow single-use plastic stethoscope by a company called Valuemed, which have been available basically forever and are for when you cannot risk getting something nasty on your good Littman)

£1.99 in single unit quantities from a dude on eBay.

These things are so cheap in bulk that they'd ship two in every box of Orthogon Gemini microwave links that I used to fit something like 20 years ago before VDSL was a thing to link fast sites to places that'd otherwise be on dialup. They emitted a quiet beeping to help you align them when they were in aiming mode; the cheap plastic stethoscope made it possible to hear that over wind noise, air handling units, and other such clatter.

I still have a box full of them, despite giving a bunch to the nursery my son went a couple of years ago.

What's the point in 3D printing something for $3 when you can buy them in a bulk box for a tenth of that?

[Animats]

Right. There are plenty of cheap plastic stethoscopes on Alibaba. There are even metal ones in the $2 range. If you want to bang out simple parts in quantity, 3D printing is not the way to go.

[throwaway2037]

Up next: 3D metal printed version!

[Animats]

Something I'd like to see from the hobbyist community: DIY injection molding. Injection molding is a process where the first one is a huge amount of work, and then you just bang them out for a few cents each. Which is why most of the world's cheap stuff is injection molded.

TechShop used to have the machine for it, but it was very rarely used. The injection molding machine was about the size of a benchtop drill press. It had fixtures to hold two dies, a pressure pump, and a guard around the molding area in case something went wrong.

There's an automated one coming out as a kickstarter. Pre-order for $6500.[1]

Now you need to make injection molding dies. This requires a milling machine, and is much easier with software support. The commercial software for planning injection molding is Autodesk Moldflow, but that's overkill for simpler projects. TechShop had that on their computers, but nobody ever used it. There's something called OpenFOAM, but it's not a nice GUI program.

[1] https://www.micro-molder.com/product-page/micromolder

[ErroneousBosh]

Isn't the pressure required to deal with injection moulding kind of ridiculous, and you need to get the die stupidly hot?

[Animats]

Yes, and yes. Yet most of the world's cheap plastic stuff is made that way. Here's the hobbyist version.[1]

[1] https://www.youtube.com/watch?v=5-tZ4l6tXPw