Cut one side of the top, so you can lay out it.

Cut out a shape like this.

Use the shape above to cut out the first shape's reflection.

Now you have to shapes.
Make a hole for your middle finger.

Try them on.
It's important to make it from an elastic fabric.

Pin it if you've found the size you want.

Now sew together the two ends of the fabric.
And that's it!