Ron,
There are some large resin printers out there. The Elegoo Jupiter ($1300)has a XYZ diagonal measurement on 17+". A 3D car would have to be smaller than that to accommodate the width and height. The Phrozen Sonic Mega ($3000) has a diagonal dimension of 21.6". The Formlab 3L ($11,000) has a diagonal of 19.3".
The printers are getting close to being able to do it. But for now the car would have to be built in 2 pieces. The F32 flatcar frame was originally done in two pieces with the deck a third piece. When we got our Saturn the car was printed as one piece. The car is quite strong without any additional strength members. The design could included a metal bar to add weight (and additional strength). There are "high strength" impact resistant resins available,
If you wanted to print the car using and FDM printer then there are dozens of machines to chose from.
Jan
PS. Creating the 3D design I feel is the real problem. It requires CAD skills plus access to the data. There are businesses that have printers that can print the model in one piece.
PPS. Found this article after I posted this reply https://all3dp.com/1/best-larg...r-stereolithography/
