I said I'd do this once I switched back to white thread

...I just didn't realize that would take almost six months to do.  Huh.

A few years ago I was inspired to make a Barbie-size version of Simplicity 8129, and I shared the resulting pattern

And in January I decided to photograph the steps to do a sew along...and finally did that a few nights ago.

Cut the pieces as directed.

Sew the front to back pieces along the sleeve top/shoulder seams, right sides together.  ¼"/6mm seams are used throughout.

Optional:  Press the seams flat, either with an iron or by opening them and finger pressing/scraping a fingernail along the stitching line on both sides.

Sew the facing to the neckline, right sides  together.  I know you may want to skip this and just turn the neckline by itself, but, lemme tell you, I am a huge fan of turning necklines with facings, because I'm really really not good at hemming such tight curves by themselves.  If you are, great!  If you haven't tried a facing before, please give this a try, OK? 

After sewing the facing, but before turning it to the inside, clip the fabric in the seam allowance, to close-to-but-not-through the stitching.  If you don't do this, physics will be against you when you try to turn things to where they're supposed to be.

OK, now you can turn the facing to the wrong side of the neck opening!  And then pin it flat, because the next step is top-stitching, and if the facing is not pinned or otherwise held in place, it may shift around to places where it should not be, only to be discovered after the top-stitching has sewn through the badness.

Aaannnd here's the top-stitching step.  You may notice that I use a straight stitch foot, instead of the common ¼" zig zag stitch foot--part of the reason I use this foot is because, when I align the edge of the cloth with the edge of the inside of the straight stitch foot, I can get the top-stitching to be really close to the edge of the item or seam.  That really-closeness makes me happy.

OK, this is progress!

Now it's time to add the lace edging.  Again, you can skip this step and just turn the hem on its own, but, for tight curves like this, sewing trim then flipping the seam to the inside is  actually less frustrating for me.  (...well...when I'm not using the rolled-hem foot, which is an entry for another day...)

Align the plain edge of the lace with the edge of the sleeves, right sides together (if your lace or trim doesn't seem to have a right side, don't worry.  The important thing is to sew the lace to the right side of the dress.)

Once the lace is sewn, open it out so the seam allowance goes under the cloth of the sleeve, then top-stitch along the edge of the sleeve.  (Technically, the seam allowance should be notched, but I don't like cutting into lace because I'm worried it will start to unravel.  Maybe I'm being overly-cautious.)

Sew lace, flip open, and top-stitch the other sleeve.

Now fold the whole thing along the arm/shoulder seams, right sides together.

Line up the front and back of the dress at the end of the sleeve, the underarm cut, and the hem, right sides together.

Stitch the underarm/side seam, leaving the machine needle in the cloth and lifting the presser foot  and pivoting the whole dress to make the turn under the arm.

Optional, but recommended:  Trim away a bit of the seam at an angle at the sleeve opening, so that the cut is close to the stitching at the very edge.  This will keep the seam allowance from sticking out of the sleeve opening.

NOT optional:  Clip the seam allowance under the arm to close to the stitching. As with the neckline facing, if you don't do this, physics will be against you when you turn it right-side-out (because it will want to spread apart, but won't be able to do so if it hasn't been clipped.)

Repeat for the other side.  Turn it right-side-out.  Getting close!

At this point, I finger-pressed the new seam allowances flat again.

Time to apply the trim to the hem--also technically optional, but makes things easy!

Stitch trim to lower edge of dress, right sides together.

Flip seam allowance to inside and top-stitch.

Almost a dress!

I like to use hook and loop tape (the generic name for Velcro®) because I like to machine sew as much as possible.  If you prefer to sew on snaps, you can do that now or wait until after the center back seam is sewn.

Pin the back seam together below opening, right sides together.

Stitch the back seam.

Trim the seam allowance at an angle the same way you did at the sleeve openings (or not!)

NOW it's a dress! (Although you might want to finger press the back seam and the sleeve seams flat from the outside...)

 Here's Charly, a vintage knock-off head on a gymnast Barbie body, reveling in the grooviness.

 This dress definitely lends itself to dynamic poses.

...eh...so...was that helpful at all?  I'm never sure if my instructions are too obvious, or if I'm completely missing things!

(Also, apologies for my cutting mat.  It's seen a lot of action.)