I have the bevel gears for my gear zine designed and ready to go, I just need a frame to hold them in position. I've started with a box, 15mm deep, with triangular tubes next to the axle holes to stop the sides from flexing. Thinking about now I realise I only need stiffeners on the surface next to the gear, that will be a modification for the next version. 

The large bevel gear, being so wide, is still prone to some side to side movement so I've placed a couple of stops near the outer edge of the gear to limit its movement.

With the end pieces in place the gears are held securely in position and rotate against each other quite nicely.