In the 40+ years since their launching, after traveling through the solar system and now beyond, what would the Voyager probes look like today if we could see them up close? Would they look noticeably different, namely due to any damage from space travel (dust/debris/rays/etc)?
The probes' various materials -- metals, polymers, thermal shielding, glass, composites -- age in various ways.
A quick summary would be hard: that question mentions the 560+ page NASA Conference Publication 3257 LDEF Materials Results for Spacecraft Applications (compiled by Drs. Ann F. Whitaker and John Gregory, October 27-28, 1992) on 6 years' exposure for 57 test specimens in Earth orbit. The Voyagers suffer less solar radiation than these specimens did, but the report addresses many other aspects of space weathering.