Hi there! It’s so exciting that your taking the pattern you love a step further and starting to experiment with it. You can make your own armhole facing to make a dress with sleeves into a sleeveless dress. You must measure the armhole of both the front and back bodice pattern and add those two measurements together. If I was to take my size of the betty dress pattern (2444), as an example, the front armhole is 9 1/2″ and the back is 9″ so that equals 18 1/2″ I measured the armhole facing pattern that came in my envelope and sure enough it was 18 1/2″ long (for my size and this is including seam allowance). The width is 2″ so that seems like a good standard for the width of your facing. So my pattern is just a strip 18 1/2″ X 2″ and I would use this pattern to cut 2 out of my fabric. Yours could be “your front +back armhole length” by 2″ and that should keep it simple. For directions on putting on the armhole facing, definitely check the betty dress tutorial starting at timecode: 1:19:53. Good luck and I’d love to see a picture when you finish! 🙂