Stretching a bit: learning how to make custom leotards, unitards and things with stretch fabrics

I took the plunge, I am stretching to new ground. Like many people who sew and costumers initially we shy away from stretch fabrics. They look great but require a different type of sewing and the fabrics behave differently than other types of fabric: they stretch.
I had made a few things with stretch fabrics before and it had not been a success. This was mostly because I used the wrong needles, did not play with the stitch length and tension and hadn't done my home work.
There are some basic things you need to know about working with stretch fabrics:
1) use the right needles on your sewing machine. Use at least a ball point needle but ideally a stretch needle.
2) play around with some scraps to set the stitch length and thread tension correctly.
3) when laying out your fabric do a single layer lay-out, making sure you flip the pattern pieces to get mirror images.

Single layer fabric layout

4) use really sharp scissors or a rotary cutter to cut neatly. Lycras often do not ravel so if you cut neatly you will have nice finished edges.
5) use fine pins (I like to use the glass headed pins) and pin only in the seam allowances to avoid marking your fabric.
6) mark the fabric carefully with outward facing clips, a disappearing fabric marker or pattern tracing paper. It makes things so much easier to match up well and saves a lot of time.

Carefully marking where seams go saves time

7) use a walking foot or even feed foot to prevent "tunelling" when stitching down fabrics.
You can stitch stretch fabrics using a wide zigzag stitch and then straight stitch just inside along the seam allowance. There are several good tutorials on Youtube (here is one that is great for the "basics" http://www.youtube.com/watch?v=ZEOjwcI5M9U or this one from Jalie, less explanation but great if you are a visual learner http://www.youtube.com/watch?v=DTZReQxc9r8). I purchased a class from Craftsy:Sewing fashion Knits beyond the basics because it dealt with some more "advanced" techniques and I can watch it whenever I want and as many times as I want so I felt it was money well spent.

baste 1/4 seams

Seam allowances for leotards are narrow,  usually 1/4", so it is important to sew them carefully. You can serge the edges but it is a good idea to "baste" sew them first. Once the seams are sewn, you can serge them. Elastics can be sewn into the arm and legs.

Front view of the leotard

Use a zigzag stitch to sew the elastics in and then turn under. Using a dual needle you can stitch down the edges, to create a finished edge.

Back view of the leotard

After posting this I went back and found that a great web-site I had found that explained a lot about making leotards and also how to draw a sloper has been taken down. The web-site called : patternschool.com still comes up in searches, and many of the pictures of the basic leotard slopers appear on Pinterest but the actual site is no longer there. I hope that it will return but otherwise I may have to try to come up with something myself.