Tangential but people might think it's neat - there's reusable indium pads for replacing thermal paste - https://www.indium.com/products/thermal-interface-materials/...

They are used on the Supermicro Power9 platform weirdly.

they're slightly less efficient than a good paste and need a higher pressure interface to seat well, but I like the zero mess aspect, ease of application, and knowing they'll never dry out

I wouldn't call them "reusable" since they do get crushed onto the chip or heatsink pretty hard and tend stick