The obnam 50 mm circular sticker contains the following image:

    https://openclipart.org/detail/28678/hard-disk-harddisk-hdd

As per the following page, it's in the public domain.

    https://openclipart.org/share

The sticker designs in this repository are all in the public domain.
Feel free to share, improve, and print them as you wish.

Lars Wirzenius (liw@liw.fi)