As one of those of us owning G1, I am full of envy. I am actually using the Lowe pro mini TZ and still I have plenty of spare place. The problem in building a G1 leather case is in overcoming the problem of its flippable LCD monitor.
Sthill there is room for Aki Asahi or others, to build a soft leather case, fitting the size of the camera much better than the crude Lowe Pro, but with the same idea. a triangular shaped case to pull the camera out at time of use.
I begg you don't force me to spend hours in doing it myself !
Cheers,
Ruben