Pandora'sBox is a mod of Beepbox that adds built-in samples via chip waves. It was made by Blue Cat Productions (although Main figured out how to import samples in the first place).
Request samples on the PandorasBox discord. Currently, there are three (official) versions that allow you to upload custom samples; The (stable?) beepbox version can be viewed here, while the (stable?) jummbox version can be seen here.
The third offical version can be seen [here](insert samplebox link here). It's updated to the latest jummbox version and has several new features, but is really buggy.