I'll be honest and say sometimes I'm too lazy to take my tray to the tray racks. Wouldn't it be great if my tray and the table I sit on just get tidied up without me having to do anything? Well, that's your challenge, find a way to collect the trays and trash from the cafeteria tables in the most convenient way. You could think about having a motorized robot come pick up your trays and deliver them to the right location. How cool would that be? This will be tough because designing a robot to navigate a crowded environment and carry cargo is no easy task. You have to make sure the robot comes to the correct table and safely returns the tray. This is a problem I would like to see solved because the tables in the cafeteria very frequently get filled with trays since no one feels like picking them up. Having the robots do this for you will make our lives so much simpler, plus it would look insane having a bunch of small robots driving around in the cafeteria cleaning stuff up.