Paper

You can skip it. Paper cannot be crafted or researched at all, so the only sheets you will see come from loot or a trade. Its own description says it goes into a building plan and a note. On the data this site holds, though, both of those craft straight from wood, and no item lists paper as an ingredient at all.

So a sheet in your inventory is junk with a small refund. A recycler hands back two to four wood for it, depending on the machine, which is about all it is good for.

The usual scene: a new teammate reads the tooltip, hunts the crafting menu for paper before a build and then wonders why it is not there. Tell them to craft the plan itself. It takes twenty wood, and nobody needs paper for it.