GitHub - arhi/gcodestat: Calculate real time needed to execute G-Code (so you know how long your 3D print will actually take), upload file directly to octoprint, postprocess file add progress report display
Calculating spindle speeds - Machine Shop Maths
gCode Visualization – Lincomatic's DIY Blog
eCut for CorelDRAW - Functions > G codes
Convert an STL to G-code for 3D Printing - Learn Robotics