ravensburger gravity comes with cardboard play fields. for it to work as toy, you remove a lot of cardboard hexagonal pieces, which we can use for other things (e.g. for children learning letters). these hexagonal pieces need storage. here is a quick design for it. have a look at the pictures

EDIT: if you print with something not as flexible (harder TPU), reduce the perimeters to 2, for me ninjaflex TPU orange with 3 perimeters works great