In a previous life, I worked in a maintenance crew in a steelmill. One of guys used to collect all of the old washers that were normally thrown away.
Seems he had one of those large (20 litre or so) 'beer can' money boxes, the type that are printed as a beer can and completely sealed except for a small slot on the top, big enough for a 50c piece.
His theory was that most house burglars are looking for quick cash and would probably not be able to pass up a large money box full of coin. Given the weight of one of these babies (even when they are half full), the scumbag thief would probably not be able to carry anything else.
His only regret was not being able to see the look on their faces when the 'prize' was opened.