I used to think they built those fantastic things from regular Lego kit stuff, you know, all rectangular pieces, double-size, half size, some parts with radiused corners, and that was all.
I thought that was all quite miraculous!
Now I discover that they're specific kits for specific objects, with custom-molded parts for special areas on the models.
My world just crashed around me. <snif>
Actually, one of my favoritest toys as a kid was the super Erector Set with the electric motor with two-speed reversing gearbox and pulleys and whatnot.

And even without all the warnings you'd probably see nowadays, I managed to not swallow any small parts.
Terry, 230RN