here's an obscure item ... a rather large (78MB) 600dpi scan of a 104 page bally parts catalog. It contains some unique line art drawings of parts for pinball, bingo, slot and novelty games.
you can download the pdf from https://bingo.cdyn.com/paper/bally_continental_(belgium)_parts_(ocr).pdf if you are curious what's in it.
ballycont_parts-001 (resized).pngballycont_parts-011 (resized).png