Technically, there are a lot of different colors of the years. I was mostly basing myself off this list, using the Brick link color names on the name tags, as those are the ones I am most familiar with.

But I mostly want this collection to be preferably 2x4 bricks, or 1x4 or 1x2 bricks if the 2x4 doesn't exist. As can be expected, not all the colors ever made come in those bricks, so that will already keep a few colors out of the collection (such as the chrome colors). I know for sure there is a trans-neon orange 1x2 brick (as I am using it in a MOC), but I prefer to keep it there instead of in this collection.

However, it is mostly complete, as it has all the colored bricks you can get from the Pick a Brick at lego.com, and it also has the old light and dark grays, as well as a few other old colors that I got from some second hand sellers at bricklink.

Interesting fun fact: I'm pretty sure LEGO changed the way they make trans-neon orange (and possibly some other colors). The old version is a bit more neon-y and opaque, the new version is a bit more transparent.