I think the gold braid makes that doublet look costumey. You could probably substitute black- even black to contrast with another body color, such as blue or green - and have a more acceptable product.

As for velvet, there are many grades, made of silk, cotton, rayon, who knows what else.... I find that it is tougher than it looks and that it will spring back readily enough with a little room and a little steam. If you are going to use your velvet doublet as either a seat cushion or as a pillow, it is advisable to turn it inside out first. In addition to protecting the velvet from drool, it tends to cushion the velvet slightly by placing one velvet face against another, rather than against something harder.