David---available, here anyway, are orifices designed to go in standard hose connections, for things like soaker hoses.
could be slid into the T before soldering. Not easily replaceable, if mayhem happens.
Some copper T's allow the copper to slide all the way through. Suspect cheaper ones. Using these, the orifices could be drilled
in the supply tube, T's slipped over, and soldered in place. But, again, not easily replaced.
Just a couple of things I've used in other applications.