I have wanted a game like this for as long as I've been gaming, and few games have ever even come close. I remember scrolling through fashion game after fashion game as a kid, trying to find one that let me design my own clothes. I did find a few that attempted something similar, but they never got into the process of the actual making of the clothes like this, which was always part of what I was craving, not to mention the surprising quality for the timeframe it was made in and the dresses coming to life in 3D instead of just drawn layers piled on top of one another.
I can easily see this demo's core with all the wonderful bells and whistles like applique, embroidery, lace, and more, not only being great as a game but as an entry point for people wanting to learn or taste test the clothes-making process without the prohibitive upfront investment of a sewing machine and supplies.
I especially would love to see a version of this that also features altering patterns for plus-sized or especially tall clients, limb differences, and more!