Investing for the future usually involves shares, houses, gold or even art. But Lego collecting is providing suprisingly good returns - maybe even better than our own stockmarket.
Lego can be a messy nightmare for some parents, but for Michelle Smith from Cambridge it's a dream job - she's making a living from being a Lego reseller.
Ms Smith has rooms of used Lego parts that she sorts and sells on Trade Me. At any one time she has about 1000 listings.
And it all started by selling a few used toys. Ms Smith says a Lego auction she put on Trade Me "went ballistic", and that kicked things off from there.
Collectors like to boast on YouTube about their Lego rooms and they will pay a lot for a special limited edition.
Ten years ago, the 'Cafe Corner' collection cost US$140 - it now sells for more than US$1500.
And the ultimate collector item, the Star Wars Millennium Falcon, cost US$140 and it now fetches almost US$4000.
Investing website BrickPicker.com tracks Lego prices just like a stockmarket, and not everyone's in it for the joy of the toy, some are out to get a good deal and resell for a good price.
So how does Lego rate as an investment? Current bank deposit rates are about 3 to 4 percent, the annual average return on the New Zealand stock exchange over the last 10 years just over 6 percent, but Lego experts believe if you really know your stuff you can get an average annual return of 10 per cent on your bricks.
But not every Lego set is a winner.
Ms Smith focuses on mini figures because they cost less and can bring a good return, and people pay hundreds of dollars for the tiny figures.
So the next time you tread on that missing brick, think not of the pain but of possible riches.