Type 4 exhaust heat shield insulating material

Im making one to replace my rusty one thats leaking asbestos. (Dont worry im being careful). Has anyone made one and if so what did you use for the middle of the sandwich - ie inbetween the metal layers?

 

Jesus. Knew id posted the question before...... in 2012 fer cying out loud. Just getting around to it!

 

How about that heat proof cloth plumbers use, I'm sure it's not asbestos any more!

 

Might use that good call .its whats inside my heat exchangers

 

Exhaust wrap ,

 

Just left an air gap between two Ali plates on mine