This is a good basic polkadot design for dobby, with the second dot offset halfway from the first. I added a hole in the middle, too, to add the possibility of a third structure. Both designs are for 40 shafts. The first one combines two 10-end granites. Max float 4.
This next one combines three weaves: a background, an outer ring, and the hole in the middle. All three are 20-end granites. Max float 4.