Designed to work with the base game only. I have laminated four player sheets to keep in the game (so each team can have one white side and one black side) and there is plenty of room for them on top but you won't be able to fit a thick stack of player sheets if you haven't went the lamination rout (highly recommended though). Below is the link to the Tinkercad project in case you need to adjust the size of the marker storage slot or something.

https://www.tinkercad.com/things/4NEHCZ5kzcz/edit