G, would you be able to do that honeycomb interior with a cast part?
No. But you also cant do it with the selective laser melting machine in the top video either, unless you leave a side open to drain all the excess powder out (or leave it in there with kind of negates the point).
In the video of the dropouts he specifically claims that they couldnt have made those dropouts any other way and yet that is rubbish. You could investment cast them for a relatively low tool cost.
Sunday dropouts have been hollow for what 6 years, and are forged for ultimate strength without needing this kind of process though there is obviously a lot more conventional work that goes into them than this.
3D printing is undoubtedly very cool and may well be a huge industry in the future, but people hyping up the (what I think will eventually be seen as) primitive stuff we have at the moment is not very helpful.
When we can lay down individual carbon atoms in perfect alignment to make pretty much anything with genuinely amazing and almost perfectly efficient strength and weight then that will be incredible. An entire bike could weigh probably just a few pounds (like 3 or 4) yet be stronger than what we have now.
G.