Step 1. Fold your fabric in half, lengthwise, as shown below.
Step 2. Cut down the middle from one end up to the folded edge.
Step 3. Serge or zigzag around the opening you just cut, then fold the edges under and hem around the entire opening.
Step 4. This last step is optional, but I like to add a few stitches to create sleeves so the cape hangs correctly and you’re not constantly adjusting. Sew 4-5” across each side (as shown in the image below) to create pseudo sleeves for your cape. [note: when we folded the cape in half to mark these sleeves, we didn’t fold it evenly, as you can see along the bottom. This creates a little less boxiness when you wear the cape, but is optional].
And that’s it — you’re done!