This link will guide you to an easy tutorial on creating your own tracks. There are 4 Episodes about creating tracks.
To use the Repl.it you need to download the main.py file into a folder.
Then you just put your .thr file in the folder too and click on the main.py file.
Note: The .thr file must have the name sandify.thr if not it will not work.
A file with the name transformed.gcode will be created and you’re finished. 
