Don’t know if anyone has seen this yet, but I came across this seller (vegito_boy) on eBay, who has created subway platforms, walls, pillars, etc from what looks like resin or 3D printing and sells them for a good price.
Here is an example: https://www.ebay.com/itm/MTH-L...TEwk_KIdnZU4oQeiAdyQ.
Pretty good looking items for someone who want to build a subway segment to their layout with the details and elements already made (that's the category that I would fall in ).
You can find his items for sale here: https://www.ebay.com/sch/vegit...amp;_ipg=&_from=
FYI - I get no financial benefit or gain from highlighting that eBay seller page.