Hey Greg
Why go to all that trouble, they sell those bottle caps with the with the draw nipple right in them. My son bought several of them, now he puts paint in the bottle puts on the replacement cap. He does his spaying, than he has some little red things he puts on the nipple and a piece of tape over the air hole and puts it away till next time he needs that color.
If you google up USA Airbrush and Supply, when you get to there site, press shop now and go to page 8 I think you will find what your looking for. The red covers for the nipple, not sure where he got those might of been Micro Mart. but I aint sure/
Hope this helps
Jeff