I once knitted a rug out of 100% cotton t-shirts that I had cut into strips. The strips were cut across the shirt, and when pulled they rolled very neatly. I tried this with an acrylic blend but it didn't roll up. I cut a hole in one end of each strip and laced the strips into one big ball of yarn! The rug was quite thick and heavy, but great for catching dirt, sand and gravel at the back door. Also good for the economy....recycling. I just did the stockinette stitch ~ nothing fancy. The carpet wore like iron, and lasted for years!

There should be an extra spool holder near the normal one, then you thread the two threads together through the machine all the way to the twin needle (I would think you could also put two bobbin threads on a single spool holder). Set the machine for a normal straight stitch. Perhaps your manual has an illustration. It is hard to describe the rest so I took pictures. It is still a bit hard to see. The closeup shows that you are looking at the outside of the garment as you stitch the hem, you can't see the hem allowance part so you have to be very careful about pinning and stitching the correct amount (else you could miss catching the hem entirely, or have too much extra above the stitching). It is tricky so practice several times on scraps! HTH Here is a link that might be useful: twin needle pictures

My older Singer has a separate throat plate that must be used for rolled hemming, or you need a special foot. ( I use the plate). The stitch length is set for a close or fine stitch and the lower looper is set very tight. Also, rolled hemming with my machine is not suited for heavy or stiff fabrics. When I make napkins, I use wooly nylon serging thread which is recommended for a smooth finish. If your fabric is not rolling, you may need a foot or another plate.

I did one of those hems on a ball dress for my DD a couple of years ago. You may go cross eyed :-) but it's achievable! Trim your hem as evenly as possible. Pin the fishing line (the lighter the line, the rufflier you can make it) about 1mm from the edge of the hem, on the wrong side of the fabric. Using thread which matches the chiffon, sew over the fishing line in a small zig zag. If you gently pull on the line as you go it will ruffle up, more ruffle or less ruffle according to how thick the fishing line is and how much you pull it. The zig zag stitch will pull the raw edge back over the fishing line and sort of encase it. Carefully trim away any extra bits of raw edge you may be left with. Best to practice this on some scrap fabric first to get your eyes in- it can be a little hard on the eyes. Good luck!