[gilmour509] posted a thorough gallery of a new custom-built computer and case made to look like a 1995 IBM Aptiva. While the whole build is impressive, the most clever part involves a 3 1/2″ floppy disk that hides an SD card and works like a regular USB flash drive when inserted into the floppy drive.
He makes use of the fact that floppy disk edge card connectors have the same spacing as SD cards. Add in a hacked USB card reader, some careful cutting and assembly, and [gilmour509] has a very convincing floppy drive with gigabytes of space.
The best part is that with everything put together, the floppy disks and floppy drive look completely unmodified. He even made the file explorer icon show a floppy drive.
The faux-Aptiva gallery includes the full build, but skip to about 2/3 down to see the floppy SD card section.