[nbadg]

I'm not trying to say that there aren't plenty of applications for small scale mechanical devices, but rather that the applications where FDM-style 3d printing would be an appropriate manufacturing process are likely to be largely biological.

Biological applications (of which tooth and bone would of course be included) are extremely well-suited for additive manufacturing because they're frequently one-offs, and therefore cannot scale, and oftentimes highly insensitive to price. Mass market products are a whole different ball game; even for applications where there isn't currently an economical manufacturing method, I'm very skeptical that there's a path where AM could be scaled out to the volumes required to sell the end component at a commercially viable cost.

To be fair though, I didn't do a good job expressing that, because I just took it for granted that it would be clear that large ratios between feature size and nozzle size are rarely economical for FDM-style AM, which isn't necessarily an obvious observation.

[kragen]

I largely agree, but I'll take the opportunity to fill in some of the other gaps in the conversation.

I didn't mean that you could 3-D print tiny laparoscopes or even visible-light metamaterials; I meant that you could 3-D print machines for making tiny laparoscopes and visible-light metamaterials.

I agree that FDM-like 3-D printing is not currently attractive for feature sizes many times larger than the nozzle size. You'd need printers with thousands or millions of "hotends".

With respect to biological applications of 3-D printing, I think you're overlooking the part of the iceberg that's currently below the waterline of economic feasibility. Biological applications of 3-D printing are frequently highly-price-insensitive one-offs that cannot scale because people don't even consider the things that will become possible when prices drop by a factor of a billion or a trillion.

[nbadg]

> I didn't mean that you could 3-D print tiny laparoscopes or even visible-light metamaterials; I meant that you could 3-D print machines for making tiny laparoscopes and visible-light metamaterials.

Huh, thanks for the clarification, that's an angle I hadn't considered.

> I think you're overlooking the part of the iceberg that's currently below the waterline of economic feasibility.

Hm. I think to a degree you probably have a point; I certainly agree that people tend to overlook the explosion of new development that is made possible by drastic cost reductions, though with the aside that having price insensitive applications is often instrumental in developing the technology that enables those cost reductions in the first place, because it allows for profitability early on in the technology's maturation, as opposed for "well it won't be profitable until we hit X milestone in Y years".

That being said, it's not clear to me how many mass-market biological applications would be possible under reasonable regulatory regimes. Maybe I'm just showing my ignorance when it comes to small-scale biological applications, but can you name some examples? (Or is this more of a "you never know until somebody does it" kind of thing?)

[kragen]

It wasn't clear to Brezhnev how many mass-market computer applications would be possible under reasonable regulatory regimes, either.