Ihave a big project coming up and now is the planning stage. the goal it to make a lego project in cadd. i am using autodesk inventor. in this program, i can make any lego piece, even those that don't exist. the project is encouraged to include movement and can include tecnic pieces. i'm looking for ideas on what to make. (a person once made a fully functional car (digital) out of lego, but that's too big) it has to be not too simple but not too complex. it can have movement as well (we just made gears this week).

ideas? comment or answer below. if you need to, attach a link or picture to your idea.