>>80771641See, having been in both sides of the equation, there's a lot to be said for how you say things.
"Dude, if you want to use our materials to do your buddy a solid, you have to pay for them the same as everyone else, getting paid for providing this stuff is how we stay afloat" is a thing most workers will get - and in fact when you generally don't even have to dock the pay, they'll often answer something to the tune of "alright, I'll pay for it then" and you'll settle tabs and things will be done, no fuss.
"If you're ever feeling altruistic again, DON'T" in a threatening manner is being a dick, entirely unnecessarily.
