I cannot wear strapless dresses. It's a fact of life that I've just had to come to terms with. Until someone out there makes a comfortable, functional strapless bra, I'm just going to have to accept that I will be adding straps to any strapless dresses that I find.
Like this one:
a fun, little, prairie-style, maxi dress . . . but no straps
I bought it anyway, thrifted, it was only 2 dollars.
To go with the prairie style, I created some ruffly, eyelet straps.
I started with some thin, ruffled, eyelet trim.
Try your dress on and determine how long you need your straps to be.
Cut 4 pieces (2 for each strap) of trim that length + a few inches extra for attaching.
Pin 2 pieces together, overlapping the center strip.
Run a zig-zag stitch down the center, sewing the 2 pieces together.
Try your dress on again, pin straps in place, and stitch down.
(I will mention this is easier to do if you have someone to help pin in place)
My now wearable dress.