I was thinking about solving the problem with feet of my quadcopter arms breaking off after hard landings. I created the more stable foot (here: http://www.thingiverse.com/thing:229300) but printing this thing with 50% infill takes 4.5h.
So I created this arm with replaceable foot. If the foot breaks, just pull the remaining piece with some pliers and plug it the spare part and you are done! Much less printing time, be faster up in the air again, save filament and money.
The foot will fit the hole very tight, so it will not fall of during flight. Depeding on your printer setup it will be a VERY tight fit.