Not part of the parts library. Parts compare specs; this page compares who is reliable: machining quality, whether they deliver on time, price tier, whether they can issue an invoice. Mixing the two would inflate the part count and turn brand filtering into 145 buttons.
Source From a community-compiled supplier directory, grouped by the directory's own categories: standard parts / misc / machining / fasteners / ESD protection / electronics / sensors / bearings — 149 shops, all actually used by the community with feedback left. There is no "well-known vendor" channel: no evidence, no listing. Quality / lead time / price / invoice are relayed field reports, not vendor claims, marked tier B. Original signatures (school + name) have been fully de-identified.