I'm sure your colleague has done this already, but for anyone considering creating their own models, I would highly recommend checking whether somebody else already went through that process for you. A lot of things have been fitted into gridfinity. And even if not for gridfinity specifically, you can fairly easily adapt other existing models to a gridfinity based box.

There are 3d model search engines where I recommend just entering [item name] + gridfinity to find pre existing models. There is: yeggi.com and thangs.com (be aware that the latter recently changed to only display models from its own domain by default).