A mini floppy disk for your A500 Mini.
I designed this to be printable and look great with a standard FDM printer using a standard 0.4mm nozzle(Prusa, Ender etc). But I've included a lot of detail(for such a simple model) that will really come out well when printing with a 0.25mm nozzle or resin printer.
A floppy disk is not just a square/rectangular thing, it has subtle curves here and there and some indentations which I've added to this.
I use a tiny amount of Blu tack inside the “floppy drive” to hold the disk in there nice a solid. You could use glue to make it permanent, or increase the height of the disk a small amount before printing if you want to really jam it in there.
Floppy Disk Label(Right click and save, print 31.5mm x 16.6mm):

Update:
Added a small insert floppy disk to look like you have a disk fully pushed into the A500 Mini. You're best printing this in a flexible material like TPU as once its inserted its hard to remove if it doesn't have any flex to it.
Update 2:
Someone has tried to claim this is their model over on Thingiverse and that I'm using it without permission(issued a DMCA takedown notice).
Here is my Fusion 360 design process as proof of design in case they try that here. Note that I also include the step files for download along with the STL.
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The author marked this model as their own original creation.