Embossing velvet is a lot of fun and I recently demonstrated this technique at Houston at the Mixed Media session. It was a lot of fun once the power came on. It is a bit hard to demonstrate with an iron if there is no power.
First I brushed some thick fabric paint onto a rubber stamp. You can use wooden, perspex or any stamp which can take a bit of heat. I have stabilised the velvet with some iron on lightweight stabiliser/interfacing. This makes it easier to cut and sew the velvet later. BTW - it only seems to work with Silk Velvet - I've tried it with cotton velvet and it just doesn't seem to work as well. My velvet is 18% Silk and 82% Rayon and works perfectly.
Now it is ready to be cut up and used in your fabric creation.
If you want to try this yourself I have put together some little kits of hand dyed velvet, Lumiere paint, a Sherrill Kahn Rubber stamp and a foam brush. Of course we have a rainbow of hand dyed velvet fat quarters too all on the