To prep them I had to soak them in very hot water and scrape every last bit of sticky glue from the labels off.
Part 1: I bought 3 complimentary colors of spray paint that was okay to use on glass. I chose a copper, gold and shimmery blue. I sprayed the wine bottles with the colors of spraypaint. No real patterns, some more than others... until they looked good to me. I did this in my front yard on a piece of cardboard and let the breeze dry them. Once they looked good to me, and they were dry, I took them inside for part two.
Part two: I took the acrylic paint and put some on the plastic. I stamped my foam stamp and rolled it on the bottles. Some areas were tricky, but I wasn't looking for a perfect clear image each time, but instead wanted to get the idea of the image. The fact that the paint was kind of drying in the jar helped give the image more depth and texture. I allowed this to dry on the bottles at least overnight. Then back outside they went to be sealed with a clear acrylic spray, in matte.
Lastly, I bought some different stoppers and pour spouts for the bottles, depending on use. I found a supplier online that was relatively inexpensive, but where I could tell I was getting a decent product. Some examples where you might use this with a pour spout: fill with some olive oil, bath gel (or bubble bath), or dish soap! (You can see the olive oil in the blue bottle above, I gave that one to my brother.) An example of a use for the stopper: bath salts or powder.
Hope this inspires you to create something for a gift!