varying degree's of fine grit "wet & dry" paper (the gunmetal color one) not yellow sandpaper.
Link as example ,not necessarily fine enough for the final lap.
I would practice on something broken first.
Is it better to use a fresh area of paper for each rotation (if following this guys method)?
2500K 4.7ghz,P8P67Pro,120gb Force3, 12gb Vengeance,R9290,TX850v2,W7HP,LaCie Blue 22" crt COMMODORE 64 Silver Label 1Mhz/128D 4Mhz(Z80)