I analyzed 1.13 million LEGO inventory records. Half of all part+color combinations exist in only ONE set and sets from 2000–2004 are the hardest to repair ever made.

I run a small free LEGO parts tool and got curious: when you lose a piece, what are the odds you can actually source it from another set? So I scored every set with 30+ parts (12,753 sets, 1949–2026) on one metric: what share of its part+color combinations appears in 3 or fewer sets in LEGO history. What surprised me most: Of 91,650 part+color combos ever made, 46,619 (51%) exist in exactly one set. Only a third of those are prints most are ordinary molds in colors LEGO never used again....