When it comes to fashion design, especially creating comfortable everyday wear like oversized tees, starting with a prototype is crucial. Using a bedsheet as a makeshift fabric to test fit is a clever and affordable method — it allows you to adjust the silhouette and sleeve length without committing to expensive materials. I’ve found that oversized tees work best when they strike the right balance between roomy and structured; too baggy, and they feel shapeless, but too tight, and they lose the laid-back vibe. Your suggestion to experiment with different sleeve lengths is spot on. From personal experience, slightly shorter sleeves can add a modern touch to a classic oversized tee, making it more versatile for different occasions or styling options. Conversely, longer sleeves contribute to a slouchier, more relaxed look that is perfect for casual days. The idea to expand this oversize concept into a matching short set and even a romper is exciting and on trend, especially for summer wear. Coordinated sets simplify outfit decisions while maintaining a chic vibe. When creating or buying oversized garments, I always check the drape and movement of the fabric. Natural fibers like cotton blends tend to work well, providing breathability and comfort without losing shape. One tip from my sewing journey is to always incorporate feedback during prototyping. Sharing your designs with an engaged audience or sewing community can provide valuable insights that might not be obvious to you. This can be feedback on fit, style, or even fabric choices. Lastly, it’s refreshing to see designers passionate about oversized fits, as many end up settling for thrifted men's shirts for that perfect look. Creating your own pattern tailored to your preferences not only ensures better fit but also allows for customization in fabric and style, ultimately crafting a wardrobe that feels uniquely you.