My way: use shearling cilppings from trimming skirts. Soak in hot water, then stuff, fingers will do. when stuffed full, keep putting more in, squeezing out the water as you go. Surprising how easily you can compact wet wool. Then pull them down and let dry (it will take a long time) When they are getting dry, you can polish the edges and smooth out the welts. When in a hurry, buy the foam inserts. BTW, my way works with any shape.