Converting a STL file into 3d Grayscale for Fiber Laser

In this video I will show you how to download any STL file and convert that photo into a compatible 3D Grayscale image, this is used to 2.5D engrave into material using your Mopa Fiber Laser
In this video I use my BWM 80w JPT Fiber laser to engrave a 3d file of Goku, that I convert from STL into a PNG file.
Please note that I am in no way an expert, I wanted to do this 48hours ago and this was the solution I found, I also like to document my finding, so I have something to reference when I forget.
Share comments if you have a better solution.
Websites used in the video
www.cults3d.com - for free and paid STL files
fenrus75.githu... - this website is used to convert the STL file into PNG Grayscale image.
imagetostl.com/ - this website is used to test your 3D grayscale PNG and see how it will look when engraved.
Have fun :)