A few weeks ago I got stranded down at the C3D office when my car wouldn't start. While normally this would just be annoying, it gave me a chance to meet some of the people down there. One of the things I was talking to Apollo about was a tactile hardware interface for the machine that implements a few features I see as absolutely essential:
I've done a lot of arduino development over the last year, and I know the GRBL is at it's heart is an arduino chip (yes, I realize it's running different firmware).
However, what I would propose is developing a hardware box, that fits on the front of the machine (should work for any of them using the same controller) It integrates into the machine using the I2C bus. I think there is a port for this on the C3D GRBL board. The device would use an MCP23017 GPIO expander.
The GPIO expander has 16 bits of IO on two 8-bit busses, which means, E-stop, jog, start/stop could all be done on one bus, and a speed control switch (just a toggle switch) can give 8-bits of speed control (0-255)
I can totally design and build the hardware (in fact, I could probably build the hardware this week if there was enough interest) however, I don't know much about hacking the GRBL software to integrate with this.
Anyone got any pointers?