Individual pieces could be pouched as well. I wondered about it too at one point, but decided to stick to hamster-safe things
Although we did let our hamster play in the Octopod during dry bathtub taming!
https://www.youtube.com/watch?v=kjyEme2xcq4
And we did use some children's toys but just for photos really and they need checking carefully (I had to block off the floor area of the army truck on this video as it was open with bits of metal tubing and small gaps underneath).
https://www.youtube.com/watch?v=nAZYfMZEzeY
I did have a megalomaniac plan at one time of a large glass tank with 30cm of substrate and the Octopod partly submerged in it
But found hamsters are more interested in cosy round hidey places and tunnels.