I've started construction of a windowed G4 Sawtooth.
I've had the computer for a few months now, and gone back and forth as to whether I should attempt this. Inspiration came from the Blue Ice G4.
Cleaning the silver off the side panels has been the most difficult task so far. The fixed-side panel (ie - not the side with the door) was scratched heavily, and I sanded the panel with 400 grit up to 1500 grit, then used polishing powders left over from an ancient rock-tumbler kit to return the shine to the plastic. Moderately successful...there are still faintly visible scratches, and it's a draw as to whether this is an improvement over having left the original scratches. The door panel will only receive the alcohol cleaning.
The Apple logos on the side panels can be removed. From the inside of the panel, there are small air holes into which a small tool can be pushed to push the blue plastic apple pieces forward. A popsicle stick was then used to pry the plastic off without damage.
For cutting the case, I made starter cuts with a dremel, but then switched to a jigsaw which was so much faster.
The non-door side of the G4 received two windows, as a support for the PSU and drive bay crosses just above mid-case. On the door side, a small window was cut below where the logic board sits, with 45 degree cuts at the upper left and lower right.
I haven't decided if the top of the case will recieve a window. It would have to be positioned off-centre (like on the Blue Ice) or very small to accomodate the door lock mechanism which links the panel latch to the back of the case.