I always delight in finding clever little solutions to real world problems that I have, the image below is a good example.
I walked inside from our front door and noticed that there was a bit of cool air coming through the door frame. Unlike our last apartment, which simply had piss-poor insulation, this door frame has proper insulation around the edges, but the door was not pressing against it.
A little piece of cardboard moving box, combined with some slicing from my leatherman, and tada! When the door is locked it will press against the frame, keeping our place a little warmer at night.
(The piece is pulled out a little from the lock for the photo op)