I hid that plastic (a description suggest that i will need it, i dunno when) in Maintenance sector, just before freighter elevator
Finishing Storage sector went easier than i realized, despite gravity panel stuff puzzle to solve and trying to guess a 3-difital code to secret stash (and there was a last camera to be destroyed).
Too bad i had to discard a SparqBeam (i think it is too weak for this part of game, but this is my opinion), and replaced it with Skorpion. I have a few hundred bullets for that sub-machine gun -still i shouldn't shoot recklessly. At least i will not worry about those Flying Bots. For now.
After entering flight level, got a welcoming comitee in form of Cyborg Assasin. I'd expect more of them. Then Loader Robot forced me to disabuse this notion.