Small cheap spring clamps are great. One flaw is that the pads always comes of and sooner or later you'll loose it. This is annoying, rendering the clamp almost useless. This design is a replacement and is meant to be put on in a different way.

Take your best soldering iron :) and melt the plastic making up the clip for the clamp, creating more of a tube than a clip (see the last picture). Put the printed pad in place and carefully insert a steel wire through the pad and the tube (former clip). Trim ends and run a file over them to remove any sharp burrs. I used a 1.5 mm stainless wire for this. Make sure the bit you're using is straightened. 

Source freecad file included for customization. The pad surface is without texture but it's easy to apply in freecad if you wish. 

Been using this for a while and it works really good. No more pads flying of in to oblivion just when you need to clamp a tricky part!

freecad > slicer 0.2 100% > pla