GDSII/GDS2 is a binary file format that represents the layers needed to produce an ASIC.
In the OpenLane flow, Magic is used to ‘stream’ the final GDS2 files.
We can use other programs or even software libraries to generate valid GDS2 files. Here I’ve used gdspy to convert
the Hackaday logo into GDS2.
You can check the very simple program out here
The Skywater PDK defines all the layers that we can use in the GDS2 files.