Speaking for myself as a crossdresser, one of my goals is to shape my body into a more feminine appearance. For this, I need to make some of my parts larger (breasts, bottom, and hips) and others smaller (waist). I wear a corset for crossdressing to make my waist smaller.
Adding to parts is relatively easy. You just buy the part and add it on. Making a part, such as a waist, smaller requires more work. Part of it is from dieting (in my case, losing 50 pounds out of an 85-pound goal), and part of it is squeezing.
My preferred method of squeezing is using a waist-training corset. The reason is that a good waist-training corset withstands much pressure, and the results are amazing. Please follow along to see how to do it.