The best storage for an example toy would probably be some form of passive torture.
This has the several advantages. For one, the torturer's re-entrance into the space represents, at the very least, hope of relief. Passivity also shows the unthinking sadism of it all. The torture continues, piles on, breaks the toy while the captor goes about their day as they please, like any other day.
A good next step, is to teach the toy what is expected of it in order to have relief from this, although the natural responses of begging and crying are perfectly functional defaults.
One great demonstration is opening a closet door to some contorted body that immediately begins desperate pleading, only to be told that it's clearly lying, and will be checked on in several hours to see if it has actually learned its lesson.
Small enclosures/cages are a basic first step; ideally the toy should not be able to fully relax or stretch its body. Then, stress positions and/or predicaments. Breath ones are fun, because the panic is deeply instinctual, and can imply to the toy that its captor is not too worried if lives or dies. Alternatively, adding an element of randomness, such as a shock collar which goes off every 5-10 minutes at a random strength. Some sort of constant pain such as rice on the bottom, grating audio, heat, etc are also fun.
Of course, any combination will always be more than the sum of its parts. š„°