* Two bottles that match (any size).
* Zipper to fit around (2-liter bottles take a 12-inch zipper, I think the skinny bottles in the pic were 20-ounces and took a 9-inch zipper - you can use a bigger zipper and cut it down but that's more complicated).
* Garnishments (googly eyes, pipe cleaners, scrap fabric, fake fur, etc.).
* Hot glue gun and glue.
* Craft scissors (to cut plastic and stuff).
* Imagination!
Step 1: Pinch your bottle on the side (not tight - you don't want the crease to stay) and cut. You only need enough cut to stick your scissors in the hole. Cut around the bottle to the size you want. The green monsters in front are just the bottom parts of regular 2-liter bottles (there's a nice line there to use as a guide). I like the tops to be short, but I like the bottoms to be different sizes. Make the cut as even and smooth as you can.
Step 2: Install the zipper. This is by far the most complicated part of the process. It looks best if the zipper is on the inside, and it's easiest if your zipper starts at the right size (you can cut it down if you have to - hot glue the end so your kid can't unzip it completely or it's a beast to get back in).
I used a process of trial and error for the zipper install, but I discovered that if your glue gun is high heat, it will melt the plastic of the bottle if you put it directly there (put it on the zipper first and wait a couple seconds and it'll be fine).
Step 3: Embellish. My sis-in-law got really creative with the yarn hair and fabric scraps, and the kids had a lot of fun with the fake fur.
My 4-year-old filled his bottle with water (the one with the orange ears) and dumped it out saying it was monster throw up. Fun times.
