I make a lot of my husband's short sleeved shirts out of fish fabrics. The pattern I had didn't fit him well, so I took one of his old shirts apart with a seam ripper and have used it as a pattern for his shirts for years. It was pretty old when he got rid of it, but I have made a lot of use of it. It had about 3/8 inch seams so I use that when making him the new shirts. They come out great every time.