Bloody hell! That's a fantastic idea. I'm 195 cm (6' 4"ish) and I've got the biggest hands of anybody I know. I've tried a grip with my 40D but the groove where your fingers go isn't continued on the Canon grip. Even the wireless grip has that problem. Yours looks like the perfect solution.
Glad you like it. yes the battery grips are great for shooting portrait, but landscape they just add more weight and bulk. I looked at different materials, plastics, rubber, ally all too heavy, the wood is very light. Someone suggested ebony wood stain and some laquer, i like that idea for a final finish, but I wont finish till I use it a bit and maybe adjust the contours for my fingers and overall size of the base.
fyi, I bought a cheap spare quick release tripod plate, cut a block of wood aprox size, then drill hole and chisel out recess space for the qr plate, screw that down onto the wood so its sits flush, then attach to camera, draw around base, remove and cut to shape, sandpaper and dremmel the contours, bit of non slip sticky back foam on top, hey presto lol... something to do when its raining I guess 


On my 40D the photos always looked better after I downloaded them onto my computer.


