I didn't have a pattern. I just cut the pants into shorts. It has a side zipper and button already. Then I used the rest of the legs for the top. I used the front picture of a pattern at sovintagepatterns.com (the Glam 1940s Bathing Suit pattern http://www.sovintagepatterns.com/catalog/item/2871951/8807586.htm).
That gave me the basic idea for the top. Each cup and strap that goes to the back is the front of one leg of the pants. The strap that borders the bottom of the halter is one leg back. But I ran out of fabric to border the entire top and go around the neck from one end to the other. I did it on the bottom edge of the halter, just not the top. The halter strap is a smaller piece that goes from the top of each cup around the neck.
Then I had trouble with the cups. They totally flatten my already A-sized breasts. I tried to put some extra darts in, but I'm going to get an old bra and insert cups. Since it's stretchy fabric, it ought to mold around it. I hope.
The back closes with a bra closure I bought at a fabric store. I was going to repurpose an old bra, but I've just moved to Australia in the last few months and still don't drive here (wrong side of the road!) and new hubby and I happened to pass a craft store this weekend so I bought the fixture new so I could finish the suit enough to try it.
The point was - other than I love 40s clothing - to cover my stretch marks. I don't have money for a new suit and all I can find are one piece suits that show too much bottom (mine anyway) or bikini bottoms with nice tops like babydolls, but those float up and you can see my baby pouch and stretch marks.
Thanks for the nice words. It looks much nicer in person and the gingham print doesn't really show up here.