Creator, C. (date of creation). Title or description of blueprint [blueprint]. Collection name/number (Fonds name/number, Series number, Box number, File number). Name of archive/library, Location of archive/library.
Smith, E. (1912, November 7). Grace Church on-the-Hill, 300 Lonsdale Road [blueprint]. Collection No. PT13-1589 (Fonds 200, Series 410, Box 140663, File 1589). City of Toronto Archives, Ontario.
⇒ APA treats blueprints like primary sources. Cite blueprints as you would archival materials.
⇒ If the location appears in the name of the archives/library, don't repeat it in the location info.