Actually @SungeunJeon I was looking for a free python suite that creates the gcode for you, not convert a macro to gcode.
Just stumbled on learn python the hard way website. This ought to be fun. . .
Good to know about the Pi 2 - I have one here that’s been sitting unused for a while, and bCNC looks like just the right thing to bring it back into service. Is it safe to assume that I’ll be able to plug my existing Arduino/gShield into it, and not worry about any of the other Pi add-on boards for functionality?
(edit for clarity - I do mean plugging the Arduino in via USB, not some weird GPIO interface or anything like that) 
Yep. You just plug the Arduino into the RPI2’s USB port. You may need to install pyserial, but the last I checked, it came with the standard RPi2 distro. So, you should only need to get bCNC on the RPi and just click the executable.
It’s also possible to directly wire the RX/TX lines on the RPi GPIO pins to the Arduino RX/TX pins too, if you want to. This would be the case if you wanted to use an Arduino Micro that does not have USB. (You may want to check to make sure it’s voltage compatible. I recall the RPi serial IO pins are 5v tolerant. Don’t quote me on that though.)
Fantastic, thanks for the info! I’ve got the Pi 2 updating as we speak (quite slowly on my crippled net connection, until my new cable installation happens, bleh), and that’s a very interesting idea about using the serial lines. I must have a proto shield lying around here somewhere…and where did that package of level shifter ICs go, just in case…? 