I think my LEGO obsession is well documented by now so I immediately jumped for joy over this key hanger from Felix Grauer. Using some basic LEGO bricks you might have leftover from childhood and some easily obtained split rings, you could make your very own based off of this nifty design.

I like how you can separate your keys out if you don’t want to carry them all and then just stack the LEGOs when you want to take more than one with you.