I used the same Burda dress pattern as my rainbow dress - bascially a princess seamed, A-line dress. The straps are from Burda too but they are supposed to be pleated and I like them sewn in flat. I had to add to the length of them, but I did make them a little too long and now they slip off.
The fabric is a wool lycra fabric that I have had stashed since my uni days. I think I would have bought it from Lincraft. I lined it in a cotton nylon fabric.