Here is the tute for the kimono dress I've drafted. I'm happy to share my tute and measurements so others can make them, but I would really appreciate if, when you make one, you PM me with the measurements you used. This one is based on 18m but I really need to test / grade it for other sizes as my only 'test subject' is dd.
Start off with a knit shirt that fits your lo, and measure from shoulder to shoulder. Make this line on a piece of paper. Draw a slight a-line down from both shoulders.
Measure the shirt you like from top of shoulder to armpit.
Mark on your pattern where the armpit falls. Measure length of sleeve (add seam allowance) and trace a rectangle of the sleeve. Cut out, you will cut this on the fold (top line).
Mark sleeve end on the other side of pattern too.
You now need to figure out where you want the shoulder seams to be. The rule of thirds (thanks Jaynesews and Petchy!) from the tute list does not apply as it needs to fit over the head without overlapping and ties. There is nothing worse than making something, only to find it doesn't fit over over their head! At sight, just over 2 in from the shoulder end looked good for me. Mark those on your pattern, both sides.
Decide where you want the kimono overlap to meet the side seam, I like it to be just a little bit below the sleeve. Draw a line from shoulder seam mark to where you want the crossover to meet side seam. Measure from armpit to this mark and replicate on other side, also making a line from shoulder to crossover mark.
I like this dress to be fitted through the bodice and then a-line, therefore I gave it a gentle flare from shoulder to crossover mark, then a more substantial flare from crossover mark to hem. First time I drafted this pattern, it was not a-line enough (it was tube like) so I cut it off to be a shirt. Successful pattern is 9ish" top line, 11ish" at crossover and 18ish" at hem.
Cut out this pattern and make a duplicate, this will be the back, set aside. Take the piece you have marked up, this will become the front. Cut along the pink line.
This piece is now left bodice, set aside.
Cut along other pink line.
This is right bodice, but it needs seem allowance added to the bottom. Trace onto new paper and add seam allowance ( have a serger so only 1/4 in for me!)
You now have front, right, sleeve and back pieces, set aside.
Return to back piece, make sure that you have traced shoulder marks on pattern. It's v important that they match up with front pieces. Fold in half lengthways and cut a gentle scoop.
I'm not entirely sure this is necessary but it's a safeguard to head fitting through and also easier to attach binding when edges are curved. It will look like this:
Lay pieces down with right sides in, aligning shoulder seams, pinning and stitching, like this.
Time for the binding, I used stretch cotton (not ribbing). It's width was 1.5 in and I folded in half and pressed.
Pin the binding around the neck, starting from the small triangle side (right bodice), stretching as you go and doing both copious stretching and pinning at shoulder seams.
Iron the two sleeves on the fold for a neat crease. Serge raw edge, turn under and hem. Match creases with shoulder seams (both facing in) and stitch. This is what it will end up looking like:
Pin right side of dress, all pieces facing in.
On left bodice, pinch unfinished edge of triangle piece with where you attached the binding before (lining up at side seam).
Starting at side seam edge (small cut) , run it all through serger again at the trim, closing the V.
Pin fully left and right sides. Serge from hem through end of sleeve on both sides, catching small edge piece of left side.
Press the binding out and steam for shape. Attach decorative button where crossover meets (or else it pops down!) Hem too!
NB. Topstitching removes the need for buttons, but I'm rubbish.
You could also serge the binding once around the neck, rather than twice. Make a small mark within seam allowance where they cross. Still starting at triangle side, run through serger until mark, pin, pinch and continue running. It was too much for me to get my head around!
Hope it all makes sense, let me know any questions!