Intro: Butterfly Surprise
UPDATE: Kiteman made one of these with paper clips -- though I haven't tried making it, judging by the photos it looks pretty good.
Step 1: 3D Printing
Like most people I do not own a 3D printer, although I do dream of it. However there are several online vendors who will be happy to print these files for you.
Out of loyalty to Instructable I wanted to check out 123D, but they don't offer Mac support and the file formats they can import are not supported by the free version of Google SketchUp which I used for my drawings. So instead I sent my file to Ponoko, where you can get them for free (the files, that is -- you will still need to pay for printing them).
You will need to print this out of durable superfine plastic: most of the other materials can't be as tiny and precise as this needs to be. The printing came to $2.63 -- not too bad -- however the shipping was over $10. I would never have ordered this if I hadn't been itching to try out 3D printing and had the motivation of entering an Instructable contest. If you just need to see what 3D printing can do, this is a good project because the pieces are tiny and cannot be made in any other way. If you're just motivated by the toy, then you might be disappointed: it is fun, but in my opinion it's not quite $13 fun.
Step 2: Materials and Tools
Besides the 3D printed pieces you will need some colored paper (I used a small piece of wrapping paper, but you could also use plain white paper and color it), a rubber band, some glue and scissors. You might also need a small file to smooth out part of the 3D printed pieces.
Step 3: Check the Fit
Once you get your 3D printed pieces this will just take a few minutes to put together:
Put the piece which looks like a hanger through the slot on the other piece, and see if it turns around easily. You may need to use a small file to smooth it out.
Step 4: Cut the Wings
Get two small pieces of colored paper (about 4" by 5.5") and fold them in four (fold it in half, then fold it in half again).
Draw the shape of the wings so that the straight edge is over the second fold. The bottom wing should be 1 1/2" (about 4cm) at the fold, the top wing (the one on the hanger) should be 1 3/8" (3.5 cm). Draw them to be about the shapes as pictured. After you cut along the lines you will have two matching, symmetrical pieces of both shapes.
Step 5: Attach the Wings
Put a small amount of glue on one side of the smaller piece and along the fold line and place it on the "hanger" piece as shown on the photo.
Attach the two larger wings onto the other 3D piece so they are glued next to the hook.
Step 6: Assemble
Slide the hanger's hook into the slot of the other piece, then stretch a rubber band between the two hooks. My rubber band was too big so I doubled it up, which works fine.