I bought a sewing magazine to gain several ready-to-make patterns. However, as usual I didn't use it much:-)
I took my old vest and made this pattern: I measured my waist and the length of the top and made a rectangle. I took the height of the armhole from the vest (20cm) and made a mark. At this point I added several cm to the width and continuously passed down to the original waist width. Under the waistline I added in similar way - a triangle on each side to flare it a bit. Then I drew the armholes and drew two halves of the neckline - freehand. So - this is it.
I sewed the sideseams directly and was trying what to do with the rest. I shortened the straps (more the front ones) and deepened the necklines. This did..
Beside knitwear I also bought a fabric that's usually used for T-shirt necks. You can take a look at how it ended up. I wasn't satisfied, the knitwear was stretched impossibly.
Well, I let the edges plain. Fortunately knitwear doesn't fray at all so it doesn't matter. I like it:-D