In the meantime, there are already some instructions on how to load (your own) MP3s onto the box. Unfortunately, you have to overwrite an existing story if you have already used Lulu. Now I have tinkered around a bit and created my own additional figures.
The 12 official figures play the files M01.smp - M12.smp on the box. I now offer the community figure sockets that play the files M13.smp to M31.smp (from M32.smp there are restrictions on the box). This means you can load up to 19 additional stories. The bases consist of a cleanly laser-cut round wooden plate with a chip at the bottom - see pictures. The chip is self-adhesive and I'm not sticking it on yet so that the base can be painted first.
I am selling the chips at cost price (2.-) - if you are interested you can contact me at yves_weber@gmx.net. I hope this will pass as a contribution to the community and not as third-party advertising...