You'd be amazed at how durable painted fabric can be. I knew I could paint fabric, but I didn't expect it too be so durable. I made these pillows in June of 2013 and they still look great after much abuse. I used Frogtape and the paint lines are perfect (when you are very careful to press down the edges of your tape).
Below are some pics of how I made the patterns with the painters tape, it's pretty self explanatory. I sewed these pillows after painting (I was too lazy to cut the squares out completely when I'd just be joining the pieces anyways). I probably should explain how I made the leaf. I placed tape on a thick, slick plastic gift bag (sort of like the paper stickers come on) and cut out the shapes I needed to make the leaf and then pealed off the plastic backing and placed the pattern onto the fabric. I then measured and masked off a stripe by placing tape on either side of the leaf. This would be very difficult to do on a premade pillow, painting the fabric while it was lying flat made this much easier than it would be to tape off a filled pillow.
The possibilities truly are endless when working with paint (and even painters tape). I come up with new patterns all the time that I'd like to try out. Unfortunately, I have more ideas than time (or focus). Keep coming back, I'd like to share them all with you sometime!