- Get a load of Lego, make sure that all the pieces are separate.
- Put the bits in a pillow-case and tie the end with some string (leaving lots of room for the Lego to move about in).
- Place in an automatic washing machine and start it on the coolest, shortest cycle (a non iron cycle is good as it doesn't get spun).
- Stop before spinning (see above).
- Remove, debag and admire the results.
Don't ask how this came about...