Takara Tomy Plarail compatible train rail cross-track designed to print on a 110mm square bed. Drawn in Inventor, exported as STL, printed in PLA and it fits well.
I ordered an official cross-track, that allows tight-radius turns as well, but quickly discovered you need 2, or at least some way to cross back over, if you want to run 2 crossing loops of track. So, I made a printable version.
(Now free. Get the bundle if you want to buy me a cup of coffee.)