So far, everything you make (as far as I've seen) in Glitch is from an in-game recipe and in-game ingredients; you can create, but only based on the choices given.
I am hoping there'll be unique creation too. Like: composing music from scratch for a music block, or making artwork for items in the Glitch world, or writing copy that characters can say, or leaving items/notes that other players can find (was there something like that in GNE?), or adding recipes and what they achieve. And so on.
(I bet this is covered in the developer roadmap but this is pre-emptive support.)