I hope you enjoy this puzzle entitled "Cornerstones."

The answer to the meta is

**something you might use to construct a building**.

Cornerstones.pdf

I suggest printing out the PDF and solving on paper. The puzzle contains unnumbered squares that cannot be accurately replicated in PUZ format. You can still solve the PUZ format, but you may have issues collaborating with others, since the numbering on the PDF will not match the PUZ. Cornerstones.puz

As always, feel free to PM me your answer and any feedback. I will post the solution on Sunday, and give hints if needed on Wednesday. Thanks!