Lego Batman's cape

I have been asked to do a Lego Batman cake, which after having made a Lego Hulk last Feb, I know I can do it without too much difficulty (hope I didn’t just jinx myself….)

My only concern is with his cape & what I should make it out of so that it keeps it shape & isn’t too heavy etc. I was thinking gumpaste and making it well in advance to dry or might that be too fragile? He’ll have to make an hour long road trip to get to the birthday boy. Maybe modeling chocolate/fondant mixture?

What do you all think would give me the best results? Below is what he looks like just in case you’re not sure of how the cape looks.

Thank you in advance for your help!