No pattern really. Here's how I did it. BTW, I added an inch to measurements A & B for seam allowance. Also, it was just too difficult to pattern the point on my sugarloaf, and since it's hidden by my crest, I just left the "top" off my mantle. If you are using a flat topped helm, just flip it upside down and trace the top to oattern that part.
1. Measure the circumference of your helm at the brow (A).
2. Next, measure from the brow to the desired overall length (B).
3. On pattern paper or the back of some wrapping paper, measure out a rectangle that is A x B.
4. Measure from the brow to the bottom of the helmet (C). DO NOT ADD A SEAM ALLOWANCE TO THIS MEASUREMENT.
5. Mark C on both B sides of your rectangle.
6. Mark a line connecting the center of the lower (bottom of mantle) side A and both point Cs.
7. Transfer the pattern to your fabric and cut out.
8. Pin the "good" sides together and stitch up the bottom and sides, leaving the last half inch of both Bs unstitched. DO NOT STITCH THE TOP EDGE.
9. Turn mantle "right side" out.
10. Turn the two top edges in and stitch the top edge closed.
11. Fold mantle in half lengthwise with the lining facing out.
12. Stitch the top half inch or so of the long side together.
13. Flip right side out and place on helm. Grab the front bottom corners and pull them back so they meet in the back of the helm. Tack stitch in place.
