I've now attached the ruched front which will extend into a halter-style strap. Actually it's not truly ruched, it's more pleated, and this was a bit unintentional - I did originally intend to ruch, but once I started to pleat it I really liked the effect, so it's here to stay. This is one of the joys of sewing - while I might start with an idea, it rarely ends up the way I first envisage!
To recap, this is a long piece of fabric, attached at the top by turning under a small hem and blind stitching so the stitches don't show. Then I pleated the fabric into several pleats by pinning it, then ran running stitches through the folded layers working from the back (underside) of the bra and making sure the stitches didn't show through on the front. I made about four sets of stitching to anchor the pleats in place, making sure the whole piece draped around the shape of the bra. If you just pin it on without following the curve it will look strange as you bring the gathered/pleated straps up into a halter style.
This photo shows the stitching at the bottom of the ruching. I haven't completed the straps, so this is just held together with a pin.
Completed ruching - I ran about four rows quite close together in the middle, underneath the bling. BTW the bling thing started life as a ring from one of those costume jewellery stores. Manly Jack was kind enough to hacksaw the ring part off (and off two other pieces that will end up in a similar way!) so I then stitched it on. To make it more secure I could put some fabric glue or gem glue on it, but it seems to be OK with two rounds of very tiny stitches looped around the diamante anchors.
I'm now going to add in some more beading and sequins along both the top and the bottom of the ruched area. This will just define it a bit more and save me from doing too much to the sequinned fabric of the top half of the bra. I'm not yet sure about adding any dangly bits to the bottom of the bra. I originally wanted to, but now I'm not so sure. It always looks great when you shimmy, but I'm just not sure what I want to do. I have another couple of bling earrings I can hang in the centre which would look quite cool - so stay tuned and see what I end up doing!