First you want to gather a few items. A mobile hanger, I got mine at Amazon here. Some clear thread, I got it in the craft area in Walmart. Looks kind of like fishing wire, but thinner. A pretty beefy needle to thread it with, and some pretty butterflies of course. I got the butterflies at Floraltrims. They're made out of satin paper, and look real.
Here are the ones I bought, and these are made from photographs from real butterflies.
Take your needle double knot it, and thread through the fuzzy part of the butterfly with your clear thread. You need to center it pretty well so it hangs well. I left about a foot of threader more to work with.
After you put together your mobile, find a place to hang it. I used one of those little screws with a hook, and screwed it into the ceiling. Then I started to mess with hanging the butterflies. This mobile has perfect little circles to thread the butterflies through. I used different lengths of thread, so they'd hang at different heights. String them up with a few knots, and you've got yourself your own mobile!
The fun part too is, you can choose your own colors. Floral trims has a lot to choose from.
Let me know if you try this, and pop over to my FB page at MJ Ornaments, and share your photos, I'd love to see them!
p.s. don't use this over a baby's crib, I'd be too afraid one could be pulled off, or fall off.