This design is a really simple case, but it can hold 3 bars of soap, shampoo, conditioner, or whatever bar soap combination you use. I've done it by modeling a basic shell and chamfering the edges. As for the insert pattern I've used Fusion 360 plug-in Voronoi Sketch Generator.
Print all elements on the flattest side, like this:
Reddit thread about my design and bar shampoos:
https://www.reddit.com/r/functionalprint/comments/wdb8lc/i_use_bar_soap_bar_shampoo_and_bar_conditioner_so/
The author hasn't provided the model origin yet.