[insipid]

I came here to say "Capsela", too. I loved those so much! (Although it's hard to tell if they still exist; the sets I could find on Amazon were so expensive, I have to assume they're the toy equivalent of "out-of-print".)

Then, of course, the perennial classics of Erector sets, Tinker toys, and Lego.

[FolioSwarm]

Yeah, Capsela I think is done, but there are replacements. Problem is I can't think of them. Just put gears into eggs and there you go. Pretty genius. This is how we should build cars, computers, everything. Just snappable parts that do something you need. Did I just say that, "Computers". How cool would it be to snap in a graphics card, software, pictures, apps, etc? Clunky I know.