im a bit worried about trying it and not getting the tension in the material and it looking saggy... esp with leather...
i might be tempted to do the sides of the seat in leather and the main section in some black faux suede effect...
its finding suitable material that will take the hammering..
Yeah, that was my biggest concerne actually. But when you insert the wires and pull it tight with other wires or clips it seems to look ok. I made a mistake when sewing one side of the center cover, because I never pinned the panel before sewing it, so it slowly gathered on one side, so when I turned the cover inside out, the bend was slightly out of alignment at the front of the seat.
So I made marks on the cloth every 100mm on each panel, then made sure they lined up with the opposite panel when I pinned them together.
Buck skin is a tough leather, that can take a serious hammering, and it looks stunning, I'm sure you can get hold of it dyed black. Falconers make their gloves out of it.

You can get samples of cloth or leathers from some companies by sending a stamped addressed envelope, a sort of try before you buy, or at least able to see if it's suitable.
As for doing an FAQ giorgio, I'll take a few photo's when I do my next base perhaps but cant promise an FAQ.