Life size AT-AT
LOL! Ditto that!
I have always wanted to see someone create one of those in true action figure size (I have only seen one person to date do this). He used a product of styrofoam and styrene at the last time he built some of these the paint work melted some things so he hasn't tried it since I don't think.
I have also seen some cool Mandalorian and Clone Trooper Armor Sets and diagrams to be make out of trash cans and what not and think it would be cool to see one of those too.
Basically take whatever you like best and create something. Whether it be drawing, custom action figure, one to one scale prop, costume, etc. the main idea is to have fun. There are lots of folks here who won't mind giving you some advice while you are working on it.