Mike, my hat's off to you for trying such an undertaking. I'd be glad to buy one from you if and when they're available!
Regarding the material, if possible, I'd suggest having it made from the same material as the original. The original material was used for a reason, and if you can make the new ones from the same, all the better.
Please keep us posted on the progress of your project.
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2003 E53 3.0i
DOB 10/15/2002
Sienna red, Savannah Beige Dakota leather
Type FA53, Engine M54B30
2018 G02 30i
DOB 4/21/18
Black Sapphire Metallic / Canberra Beige Vermasca leather
Engine B46O