Build a new diaphragm for M horn

So at the beginning of 2020 I picked up this M5 off ebay. It was sold at a pretty decent price, but when I got it I discovered that it was missing one of three diaphragms in the #1 bell. I looked all over but wasn't able to find a replacement, so I got the material and made my own. This is a 6" X 25" sheet. McMaster-Carr part # 9014K315 (accurate as of May 2020) This video is part one of three. Part two, parts and anatomy:    • M Horn Anatomy and Parts   Part three, voicing.    • M5 Horn Voicing (M5 Tuning)   Part four, full air tank runby:    • M5 Chip Tooth Full Air Runby