This morning I had an idea. Last night I was dissassembling a huge bagful of insulin pumps (my cousin is a diabetic and he uses them, cleans them, and gives them to me to take the guts out of them) and in them I keep the springs, casing, and insulin resevoirs... (I ALWAYS throw those horrid needles away; I don't want to get stuck with one) I had an idea looking at the resevoirs... I wanted an ink pen that could write/draw in ANY color ink with the turn of a dial, adjustment of a slide, etc.. anyway, I have about fifty of these resevoir things (they have little pistons in them) and I was curious if there was a way to reach my goal. Should I use red, blue, yellow ink, or should I use magenta, cyan, and yallow? Do I have to make the inks myself, or could I drain them from printer cartriges? Should I use only primary colors, or secondary colors as well?