I've got my leather, a piece of 1mm Kangaroo as below
I think it might be best to cut it into two 145mm high strips, giving me 10mm to sew along.
I'm not sure on the best way to do the weight would be.
If I use the exact measurements of the passport plus flaps, it will be too tight once sew together but I don't to add, say, 5/10mm and it be too big.
I could fold them around the passport as tight as I can, and clamp them in place but I can see that getting messy an wont be very even.
Thanks for the info on the tools, I'll get those ordered.