Update 8: RESIN
Combine Resin added.
Combine Resin is used for a number of recipes previously exclusive to the Combine. Recipes such as these need a Combine Fabricator to function - a workbench that'll be added in a later update. For now, the Workbench in the CiviPro HQ functions as such.
Due to this, all COMBINE restricted items are now no longer restricted, as they require Resin and a Combine Fabricator instead.
Resin can also be used in events to repair combine machinery, power dead terminals, and a whole host of other things. It's really handy to have around!
Resin is common for the Combine - each week they get 20 of it, and unlike their other supplies, it isn't wasted if unused, so keep saving it if need be! Though do note - the only container in HPR that is raidable is the Combine Resin one.
Rebels - Resin is an extremely rare, hard-to-find resource. You know what they say about Resin - Look for more resin.
It'll most likely be given through
french elephants fringe elements in the CMB faction, like rogue cops or resistance members in the engineer corps.
Of course, it can be obtained in violent ways - raiding engineer workshifts - raiding the HPR, even - or salvaging combine machinery after some kind of raid.
Recipes have been updated on the document.
Additionally:
Weapon upgrades!
You can now upgrade weapons from their 'lesser' counterparts into better versions. For example, turning a Benelli Nova into an M1014, or a USP-M into a USP-T! These all require Resin and a Fabricator, though - so get to work!