Welcome to the SeeMeCNC Community

This is something that I've been working on for my Ultimaker for a while, and its working, and I think its pretty cool. It works for Marlin right now, and I have it connected to a RAMPS board, but I'm sure you clever devils here could figure it out for your RAMBo's and MAXes, and if I do some poking around I could adapt my code for Repetier.

I used the diagram on card 5, the one with the 12v LED strip and MOSFETS.
http://pgdev.pighixxx.com/ABC/SET/s2.pdf

I got the resistors and MOSFETs and LED strips and soldered the resistors and MOSFETS and some terminal connectors I got at RadioShack onto a generic solder breadboard I got at RadioShack as well. Ill include pictures of the board (and my terrible soldering skills (I have reeeaaaally shaky hands)) later.

I used AUX-2 on my RAMPS if anyone is using RAMPS, though any pins should work on RAMBo as long as they aren't dual function (obviously). I used 3 digital pins and one ground pin, and a separate 12V wall wart.

I programmed it so that if ANY heaters are ON, then the RED LED is ON (Heating), if ALL heaters are OFF, but ANY heater is above 53C, then the BLUE LED is ON (cooling), and if ALL heaters are OFF and ALL heaters are below 53C, then the GREEN LED is ON (Cool).

Pictures of the cool LEDS on my Ultimaker follow

That looks really cool! Like I said before, you have a great future if you get into the right field.

I'm considering doing something similar with my MAX once it gets built by plugging in a 5-channel RGB LED driver board into the spare I2C header on the RAMPS board (or Rambo.. not sure which I'll use yet ). The though crossed my mind of having zoned LED strips which change colour based on the state of the machine, kind of like what you have but 5 zones! The schematics for my board can be found here if you're interested: https://github.com/gjorban/ProsthesisSc ... ED%20Board

EDIT: Also, the matching library I wrote for it: https://github.com/gjorban/ProsthesisAr ... thesis_led