What counts as a Lego piece?

[Hamslice]

So here I am, building away on my not so secret steampunk creation, and I'm looking for a big round lid for my water holding tank and what do I see? The pick a brick cup lid, and it fits perfect! Not only that it's clear enough to show Lego water through it. But does it count as a legal piece used? Cause it's made by Lego you can only buy it at a Lego brand store too. So is it ok to use?

[Captain Pike]

Go for it! There are also the various bionicle container and toppers.

[timtosino]

It even says LEGO on the top stud doesn't it?

[AC]

Someone has to do it first.

[Hamslice]

Good call, thanks guys!

[Claybricks]

Just out of curiosity, do you have any pictures of your 'not so secret steampunk creation'? Or do we have to wait until it's done.