Build 3-Axis CNC MACHINE

I have 3 axis CNC machine which works with arduino mega. For testing purpose I have tried some codes. it works code but I need to well coded project (controller + g-code converter from stl file) 1. I will upload 3D model (STL file, I think STL format better than others ) to the converter. 2. This program will produce appropriate G-code for our 3-AXIS CNC machine (drill ). 3. We will send this code to controller in order to start to cut wood for given model. 4. it should show working area on computer. for example what it is doing right now, at the end it will be helpful to see result on computer and on wood.