Thingiverse.com is LOADED with “things”.  There are some great nuggets in there if you are willing to sift through the large volume of random, incomplete, bad and ugly.  Some of this is in the eye of the beholder, but I really want my designs to be BOTH functional and have a pleasing form.  Bevels, rounded edges and curves are all great tools to take your design to the next level.  Imagine a car designed with only 90 degree angles.