I’m amassing quite a stockpile of unused circuit boards, some with major design flaws, some with minor issues, some use obsolete parts. Others have no issues but have been superseded by more robust designs, or finding something on ebay that does the same thing for a fraction of the cost.
I use them as ice scrapers. Small (particularly circular) ones as coasters to protect tables from wet glasses (although the water runs through the vias so this is not 100% effective.) I’ve made one into a clock face.