Harry Potter

I'm working on a Harry Potter illustration thingy. I'm basically trying to create as many objects and stuff from the books/movies in my own "consistent" style. Then all these objects will be arranged to look like a silhouette of Hogwarts castle. These are the ones I've done so far (look at the attachment), I'm not so sure about the envelope though.

(I'm not very good at this... I'm kinda getting better along the way, trying to develop the style as I go along so there will be many changes made. This is all practice for me between client projects and it's quite fun atm).

Feedback and all that is welcome, I'm not sure I like the colours at this point either. Also tell me your favourite objects/things, I'll draw 'em :D