Quizland

Simple solution. Get an elastic band and stretch it over the can so it's positioned over the middle of the opening, then remove the excess paint from the brush on the elastic band

paint-with-elastic-band.png

I made a similar gadget with a coat hanger.

Also put a mark on the lid and on the side of the can before opening it.

After cleaning the inside of the lid after you paint replace the lid lining up the marks.  It fits better.