This top is made by working a variation on traditional granny squares (the gaps are slightly smaller, so there are less overall holes than you would see on a granny square), joined together to form a band for the body, then a series of chain bars and trebles to create the top and bottom edges.
The instructions are for DK yarn, and our samples in the photographs are worked using Drops Muskat cotton. Tension details are not included, as this gives you flexibility with the yarn you might choose.
Garment chest measurements given below are based on each square measuring approx 13.5cm so if you wish to create greater chest width, you can work an extra row of bars and an extra row of trebles on each square or work more double crochet on the back button loop strips.
You can also increase the length of the body of the top, by working extra rows of the trebles and bars that form the top and bottom edges.

You will need:
DK: 50g balls 2 (3, 3, 4), if using one colour. If making multicoloured, you will need 1 ball of each colour.
Hook size: 4mm
Buttons: 1 or 3