What's the rarest or most unusual computer-related item do you own?

[steven at malikoff.com]

Somewhere I have (misplaced) a BCROS card from a 360/50. Beautiful, intriguing
thing... haven't seen it in years unfortunately.

Also a pair of earrings made from two IBM 1403 chain printer type slugs my dad made
for my mother many decades ago, long before 'retro tech jewellery' became a thing.

An australian S-100 prototype board for the SC/MP CPU, rescued from the rubbish bin
at Applied Technology (who later made the MicroBee) as it was a failed PCB etching.

Steve.