Here's a quick tutorial on how to set set project environment variables. I tend to do this at the beginning of the project and use the .bat as a launcher whenever I need to open a file for that certain project.
Here is a link to some variables. There are many more undocumented variables
Katana Variables:
https://learn.foundry.com/katana/dev-guide/EnvironmentVariables.html
Mari Variables:
https://learn.foundry.com/mari/Content/user_guide/extending_mari/environment_variables.html
Nuke Variables:
Maya Variables:
https://github.com/mottosso/Maya-Environment-Variables
Houdini Variables:
https://www.sidefx.com/docs/houdini/ref/env.html
Substance Variables:
https://docs.substance3d.com/spdoc/environment-variables-172823292.html
Here are the common ones I use for Mari
SET OCIO=insertPathHere
This sets the config.ocio
SET MARI_CACHE=insertPathhere
This one changes the cache so you wont be working out of your documents but instead out of a folder in the project location