Yeah, there are a few hard parts that I left out. Making it 'good enough' is hard, but for a reason I found surprising when developing the methods. Making the design look exactly right is quite easy, but making it
feel perfect is damn-near impossible. The way it bends and the texture in your hands are qualities of the exact manufacturing process and materials, and you can never quite nail it with a knock-off.
That said, most people will never hand them to a customs agent, and I had reports that mine were accepted as ID by police officers on several occasions. Maybe the forger is more sensitive to the differences than most.