I like a cozy sweatshirt or t-shirt as much as the next person. However, I absolutely loathe all things up on my neck. From mock neck sweaters to scuba diving hoods, I'm out! I also hate wearing headbands. The fabric ones are too tight, and the plastic or metal ones dig into my skull in so many rage-inducing ways.
I loved the muted color of this sweatshirt, and the collar felt like it was chocking me. Not to mention the tags really pissed me off. So, I cut them off and made a spiffy coordinating headband that keeps my hair from annoying me. The headband is soft and doesn't have a lot of pressure on my head or jab into my skull behind my ears. Yay!
Suck it, sensory issues.
check out a thrift store to find a sweatshirt or t-shirt to practice with before cutting into something dear. Choose a fabric that won't unravel like fleece, t-shirt, or sweatshirt material. Follow the edge of the collar closely, and that will become a headband. Take off a centimeter at a time until you've got it just right for what feels good to you.
You can go shallow and wide with your cut for a boat neck effect or narrow and deep for a scoop neck look. You can even go full 80s Flashdance, if you've got the urge. If in doubt, mimic the shape of the bottom half of your face or jawline.
I've been known to cut down t-shirt sleeves to a cap sleeve for range of motion or trim the bottom of a t-shirt so that it doesn't give me unflattering lumps or chafe when tucked into my pants. I like to have a scoop shape on the bottom of my t-shirts and tanks when I wear them untucked.