With that in mind, I took these two shirt muslins and made them wearable. The embroidered one, I made last autumn and wore with the ill-fitting sleeves. The pleat-neck one, I think I've got the sleeves worked out, but don't have the same color fabric for them, so this too will be a sleeveless tunic.
As you can see, either because of the shape of my shoulders or because of a design flaw in the pattern, the back arm hole gapes. Previously, I've tried using elastic or darts to fix this. The elastic works well, but I want another option. The darts make funny shapes on the back of the shirt. This time, I tried gathering, putting the most gathers in the back and trying to make the front smooth. This distribution didn't work out perfectly – the fabric had a mind of its own about where it wanted to go. But, I'm pleased with the gathering. I still want to find a way to make a sleek finish to sleeveless shirts, but I feel as if I'm making progress.
For the embroidered shirt, I also cut the neckline lower and finished it with self-made bias tape. Now the front neckline gapes a bit, but it is much more comfortable to wear. Also, I cut the front arm hole in towards the body by one inch. I think that helped reduce the wrinkle that was going towards the shoulder. I want to transfer this to my paper pattern and see if it helps next time I cut a muslin.
For the plain shirt, the neckline shape is because there was too much gaping and I couldn't figure out how to get rid of it in the cut fabric piece, so I created this solution.
For both these tunics, I think I need to lengthen the pattern by one-two inches, especially if I keep the side shaping.
These are muslins and not my favorite garments, but I try hard to make wearable everything I sew. I dislike wasting fabric. The sheeting is cool in the humid summer, so these will serve for those days that I'm staying at home or doing dirty work.