There is no limit to what can be painted. Even fish get a coat if they hang around long enough.
I'm painting basecoats on plaster of Paris fish ( latex based stabilising solution plus 2 coats of acrylic wall paint). Once prepared an artist with a brush comes along to do their stuff. Then I protect it all with 2 coats of clear exterior satin varnish.
About 40 of these will be on poles, minus masking tape, as part of a huge art installation #fish #paint