What would you put on this shef?

I just bought a new house and there is one shelf over the stairs. For reference, it's 15cm (6 in) width and only the right half is easly accesible.

Thank you!

I just bought a new house and there is one shelf over the stairs. For reference, it's 15cm (6 in) width and only the right half is easly accesible.

Thank you!