I think that painting pvc is the wrong way to go. Plastic and paint don't really mix.
I can think of two possibles... 1. Sharpie--obviously you only draw on it in strategic places. 2--(oddly enough) Dye. I'm not sure of pvc, but many plastics are porous, and will take dye, or stain, better than they take paint. Might be worth some experiment.
The Lady with a Lamprey
"The powerful are exploiting people, art and ideas, and this leads to us plebes debating how to best ration ice.
Man, no wonder they always win....." Lonesomebri
Get a Taint, you pathetic cur!