Everything you need.
Measure where you want the tutu to sit. Subtract 2 inches for a smaller tutu, and 4 inches for a larger tutu. When you tie on the tulle, it will stretch and become larger.
Overlap the ends of the elastic by an inch, and sew them together on a machine.
Not perfect, but it'll do!
Place the elastic around 1 or 2 gallon jugs, depending upon the size of the waist band.
Measure the tulle into 7 inch segments, and cut. If you don't have a board like this to measure on, use a measuring tape, and pin it to mark every 7 inches.
Place your 7" stops of tulle in neat stacks. I used Static Guard to get them to lie flat.
Gather 3 pieces of tulle, and open so it is only 1 layer, not folded.
Place tulle around elastic to tie a knot.
Tie a knot, like you are starting to tie your laces.
Next, add 1piece at a time, but don't open the fabric--keep it 2-ply. Do only 3 single pieces (one of each color) and then add another long strip just like the one in the previous step.
Follow that pattern until you have 5 long pieces (LsssLsssLsssLsssL). Then, continue all the way around with just the shorter (folded, single-ply) pieces. This will create a longer look in back.
Here is a front view of the finished product.
A back view, but you can't see the longer layers in the back yet...
The longer layers.
Tutu...I will post a pic of Tweedle Dee and Tweedle Dum in costume, when it is complete.