Yeah, it works very well for stuff... Also, dress forms are expensive to buy and duct tape and an old (or cheap, new) t-shirt are very cheap. In some ways, it works better than a dress form you buy because it really is molded to the person's shape.
but yeah... I've done a lot of creating sewing patterns... especially every Halloween lol... you should see some of my daughter's Halloween costumes. She's cute in them and loved every single one!