I'm lagging a day or two (and counting) behind the MPB Men's Shirt Sew-Along, but I did get started yesterday. I traced off my pattern and marked it up. Negroni is probably the wrong style altogether for DH: The chest and waist measurements for any given size differ by 8", while DH's chest and waist measurements are the same! The muslin will be composed of pieces ranging from S (cuff) to XXL (body). I've also decided to try one long sleeve and one short: DH wants short sleeves but I want to learn to put on the cuff.
Here's an action shot of my tracing with handy Tomato Paste pattern weights. They work quite well. Small mammals, however, do not work very well, no matter how willing they are to volunteer.