Can one make his own fuel injector cleaner?

Can one make his own fuel injector cleaner?
Of course, but 50 years of schooling and experimenting are in that $5 bottle from the auto parts store. Most have varied combinations of surfactants (detergents) and solvents (like acetone, naphtha, toluene) in a kerosene base that has a long enough residence time on fuel system components to dissolve the "gummy" buildup that can truly plug carb and injector passages. They do this effectively only if used with regularity over a long time (months to a year). CAUTION: the commercial formulations are designed to not toast the emissions components (oxygen sensor, catalytic convertor) on modern cars, so their is no cost savings if you mix wrong proportions. Pre-emissions vehicles have less to worry about, however, the "home brew" might still burn a plug or crack a piston if mixed with too many high volatile solvents.