Christmas tree valve assembly and gutenberg printing press: what they have in common

1. Step 1. Christmas tree valve assembly — is part of — Oil well. Valves at the wellhead.
2. Step 2. Oil well — is used in — Crude oil. Oil is extracted from wells.
3. Step 3. Crude oil — is material for — Polyethylene. Made from petroleum products.
4. Step 4. Polyethylene — is material for — Tetra Pak. Polyethylene.
5. Step 5. Tetra Pak — is made of — Paper. Cardboard.
6. Step 6. Paper — is used in — Gutenberg printing press. The impression is made on paper.

Open Evothings