Some mistakenly thought my wave-y welts were ric-rac; well they're not! I made them myself!... although if you do have access to such a thing as giant ric-rac (I have never come across any such thing! but then Perth is a small place) then I suppose you could use it for these welts if you want... As it happens I did take a few photos during the process of making these... partly so I could have a record myself of how I did it since I was doing this on the fly, but also just in case anyone was interested in making their own shaped welts for a pocket... and some were, so thank you so much for asking!! :D
I had laid down my hand and drawn around it to get a pocket piece; and based the length of my welt on the length of the opening edge of this piece... and then drew out the shape I wanted for my welts on paper... this is a sine wave... (that's my geeky side coming out for you there, yup, I am a fully paid up member of nerds anonymous) Note; that although my shape is a sinuous curve; the four outermost corners of the design still form an exact rectangle... having this will make it easier! I also cut out four large-enough rectangles of my fabric and applied iron-on interfacing to two of them.
Draw the design onto the interfaced piece, do the second one as a mirror image. Pin an interfaced piece to a non-interfaced piece, right sides together, and sew as slowly and as accurately as possible along your marked curves.
Trim and clip along the curved edges and turn right side out. Press; with your finger inside to ease out those curves to sit smooth and even. Voila; welts! Well; potential welts... hehe, hang in there :)
Now I tried on my dress and pinned the welts onto the outside of my dress where I wanted them to sit; so they were in a comfortable position for my hands. This is an individual thing... for me it is at about hip-bone height, but it is also a toss-up as to where you want the welts to sit aesthetically, to be in a visually good spot on the dress. I find a comfortable spot for my hands is quite wide-set, but I still wanted for both the welts to be quite visible at the same time from the front view of the dress...
Mark the corner points of the welt design onto your dress with pins, and check to make sure that your two marked rectangles (which are your welt positions) have the exact same dimensions as each other, and as your paper piece... also that your two welt positions are exactly equal distance from the side seams, have the same "angle" and are exactly level to each other on your dress (sorry if I am stating the obvious, but it is best to say it than not...they are a pretty stand-out feature and wouldn't it be awful if after all your hard work one was "off'!) I reckon it is also a good idea to double check on the inside, where it is easier to tell inaccuracies since the visual distraction of the actual welt is not there.
Carefully snip (the dress fabric only; be careful not to snip into your welt!) down the middle line of the marked rectangle, and in shallow angles out to the corner points. The shallowness of the angle cuts to the corners should be dictated by whether of not you have a sharp inner curve of the welt at the corner; cut the corner angle accordingly to be hidden by this... Join one pocket piece to the inner cut edge of the slit. I joined mine in a French seam, but that is only because I am sometimes obsessive about raw edges.... this is not strictly necessary... then pin the inner edge of this seam to the underside of the welt.
Now for the other pocket piece; at this point I realised it needed an "extension" for it to fit properly inside the welt and onto the the other pocket piece, so I cut a rectangle of fabric for the second pocket piece and joined them in a French seam, then laid down the extended pocket piece onto the first pocket piece, aligning those French seams and the raw pocket edges...
Turn in a narrow fold on the other long cut edge of the slit, and press.
Lay the extension on the second pocket piece over this fold, to be nice and flat and even; and pin the top single layer of that new fold together with the extension piece of the pocket... sew together in the ditch of the pressed fold.
I trimmed down that long free edge of the extension piece and tucked in the raw edge and folded the extension piece over and enclosing this seam allowance, and pressed and topstitched it down in the ditch of the previous seam, thus enclosing all raw edges. Yeah, basically a flat-felled seam... :)
Finally laid those two pocket pieces together, pinned and sewed together around the long curved edge.
On the outside; turned under the small snipped triangular top and bottom edges, and pinned and finger pressed them into place...
On the inside; carefully transferred the pins to the finger-pressed folds and stitched the short raw triangular ends to the welt allowances, keeping everything else free.
On the inside; invisibly fell-stitch the inner (unextended) pocket piece to the inside of the welt piece
On the outside, and using matching thread, invisibly fell-stitch the outer edge of the welt to the dress.
On the inside, trim the welt edges even with the pocket seam allowances, and enclose the seam in a HongKong seam. Not essential, but it does look so much nicer and well finished, doesn't it?