Hi: That is a very nice job, and should be safe.
One suggestion would be to turn the box tubing on its edge, so the can would rest in a "V-Block" and not roll away from the puncher tool.
That said if a cylinder is to fail it is usually the long seam on the side, and punching the side might cause this. Your box tubing protects you then.
If I want more paint out of a spray can, I punch a hole in the edge of the top. Then I can use the Awl as a needle valve to let the pressure out. When the pressure is low, and this take a while since the propellant is in the paint, I punch a second hole. With two holes you can pour the paint out. Use it quickly, it is only good for an hour or so. I tried to save some in a jar and the paint volume was half the next day.
Stay safe! Carl.