Some time ago I designed and sew the summer dress for me. I used a cotton batiste for that project. I made a simple strap too, I can tie the strap at the waist. Here is the effect:
Version without strap:
Closer view on the strap:
The top frill has an elastic, which holds the frill in place nicely. You can see the top frill closer here:
And what do you think?