You don't need to make two dies. All you need is one. Take a piece of soft rubber or urethane (you can get different hardiness) Place the part on the rubber then ram the die. The rubber will conform to the die pressing the metal. This may take some practice on what hardness rubber but the end result will leave no marks on the aluminum piece. I have a long urethane die I use on my press brake that I bend painted aluminum sheet on and the die leaves no marks.
Here's a picture I found on the web of what I was describing.
