Here is a hand picked selection of links to websites about cardboard and cardboard related stuff.

Corrugated.org - The official organization for the corrugated cardboard industry. You can get news, videos, and lots of information from their website.

Amazon has taken initiative to reduce cardboard waste in their shipping. They have done a lot. Learn more about it right here: Amazon.com cardboard and waste initiative

The Cardboard Bernini - This is a documentary on Amazon Prime. It is about an artist (James Grashow) who spends four years building a reproduction of a Bernini fountain. Gian Lorenzo Bernini was a Baroque sculptor. Fascinating documentary. And the whole thing eventually melts in the rain.

A company called Zonon sells a variety of cardboard sheets in 50 packs for very reasonable prices. You can get it on Amazon. They identify it as brown corrugated cardboard which is a perfect description.

These sheets are often used as a divider in shipping boxes or as a support in shipping bags and packs but we can use it superbly for crafting.

Here is their amazon page: Cardboard sheets by Zonon

You can't buy the official amazon boxes. You know, the ones with the smile on them. Possibly you get them shipped to you on a regular basis so store them away! But, you can buy any imaginable size box from Amazon. Although because there are so many it can be a daunting task. Here is the main box page on Amazon.

If you are curious about official Amazon box sizes I have a chart with pictures right here: Amazon box sizes.