I use a wooden Indian stamp. I've had a few of these sitting around doing nothing for years.
I ironed a stabilser onto the back of the velvet. I like to stitch it stabilised and if you iron on the stabiliser after you emboss it takes away a lot of the design.
Lay the velvet face down onto the stamp.
You can also do this with silicon stamps and if you brush them with fabric paint you can emboss the painted design into the velvet too.
Try it yourself with some of our new hand dyed velvet