First, gather your supplies. In this case, they are very limited. Tissue paper in various colors, chenille stems (pipe cleaners), good sharp scissors, and sewing thread. Not pictured is a wreath to hang them all from and ribbon to hold that up. I got a wreath from the dollar store, but a couple of twigs twined with ribbon would work well too.
Cut your pieces of tissue to 9 inch by 6 inch lengths (or thereabouts... it doesn't have to be perfect by any stretch) and pile three on top of each other. I always put the contrasting color in the middle. I think it makes a more subtle change of color for the mobile, but honestly, you can do it any way you think would look nice. Fold them in half.
Then cut roughly this shape (above), the only thing you have to remember is because you are going to gather them, you want the top to be pretty strait across so it has room to gather nicely.
Fold the chenille stem in half, and tie a piece of the thread to the fold.
Tuck the three butterfly shapes of tissue into the fold of the chenille stem. At this point, gather the tissue up so it is about 1/3 of the way down the folded stem. Then twist the stem at the 'head' of the butterfly.
Fold both sides of the chenille stem back to form the antennae and tie the other end of the string to just above the tissue the neck of the butterfly. Cut off all loose ends of string, and fluff up the wings by separating the gathered tissue.
Rinse and repeat until you have all the butterflies you need for your mobile. :) Put them at varying lengths of string so they hang in a spiral shape up towards your wreath.
To hang the wreath, tie four ribbons opposite each other at the top of the wreath making a square. Then tie them all together, being careful to make sure the knot allows the wreath to hang level. Connect your butterflies and your done!