This was actually a lot more difficult than I expected it to be, but I did come up with something. The design principles are the same as for rectangles:
1. Corners need 3 sc or 5 dc to be square
2. It's easier to feel a chain 1 than to feel the middle stitch
3. Dc are twice as tall as they are wide
Essentially, this is a rectangle where the initial side consists of only a corner. So, what you have to do is make a corner in each color in the same chain space, then crochet down the opposite color's corner and make another corner.
Here's that concept written out:
Round 1: (dc, ch 1, 2 dc) in 4th ch from hook with color A. Attach color B to same ch, (ch 3, dc, ch 1, 2 dc) in same chain
To make sides: dc in post of opposite color's starting ch 3, work corner (2 dc, ch 1, 2 dc) in top of opposite color's starting ch 3.
Round 2: dc around with (2 dc, ch 1, 2 dc) in the ch 1 of corners
Repeat Round 2 until work reaches desired size.
I made this with Bernat Baby Coordinates in Tangerine Dream and Funny Prints with a J hook.