On tuesday and wednesday I made a petticoat from two old lace curtains I bought from a charity shop for 2 euros each. I wanted my skirt to be about 60 cm long so I cut the curtains into strips 22 cm wide (20 cm + 1 cm on each side to be sewn). With this width I would need 3 rows of 20 cm strips. Here's one of the curtains folded in half, the strip meant for the bottom part of the petticoat already cut out. The rest of the strips I cut horisontally.

I measured the bottom strips and got 7,6 m, then I put together the next row of sprips and made it half the lenght; 3,8 metres. The top row in turn was half the lenght again; 1,9 metres.
I sewed all the pieces of each row together to make 3 rings of fabric. I then pinned together the middle of the back of the top row, with the middle of the back on the middle row. Then I did the middle of the front of both layers, then the middles of the fabric in between and kept going like this until I had a manageable amount of fabric pinned together for sewing. As one layer is twice the length of the other, the pinning will look something like this;

Of course I couldn't be bothered to put the pins this close to each other anywhere else but on the elastic I used for the waist, but maybe you get the idea? The rest of the fabric (loops sticking up) I wrinkled by hand as I sewed.
After pinning together the two strips at the top, I sewed them together. The I did the same thing with the bottom layer, pinning middle to middle, middle to middle and finally sewing the layers together. Here's the result;

And after this I pinned the top layer to the elastic (as seen above) and carefully zig-zagged it to the elastic, stretching it a little as I went. I used zig-zag here because I want the thread to "stretch" when the elastic stretches and not snap and make the whole thing come undone.
Here's the finished petticoat;

I chose the curtain I did beacause of the ready made ruffles, which meand that I didn't have to line the full 7,6 metres, phew. And it looks pretty cute too!
Now this is not the most poufy petticoat imaginable, but with longer strips it would have been. It all depends on how much fabric you wanna use (or how long your curtains are)! I'm pretty happy with the result though, as I have got a cotton even less poufy petticoat, that I can combine with this one should I require more pouf. And that's how I made my first petticoat! Feel free to ask if there's anything that left you wondering!