Mosaics brainstorming

As I am beginning my mosaics project, I have begun to research many ideas. I have come up with four possible designs: 

 

I used the site Pinterest to look at large and small scale mosaics. Of corse all of the designs would have to be modified in order to successfully be created. I would simplify the design I choose in order to make it more realistic for me to accomplish. I also need to start gathering materials, preferably glass. A challenge I might face is shaping the glass pieces to fit my design. A hard design would be the earth because I would want the exact shape of the continents. Another one would be the castle because you need straight edges for the tower. Overall I think whatever design I pick will be a challenge.