Printable UDH hanger.  Not sure that I would trust a printed hanger long term but if you need it for a ride and can't get to a bike shop it could be the ticket.

I should clarify that this is not a truly universal hanger.  Universal Derailleur Hanger is a trademark and this hanger will only work on bikes that are designed for UDH.

I printed in PLA as proof of concept but would recommend the strongest material you can print with.  The derailleur mounting threads are too fine to print well.  I ran a M10x1.0mm tap through to mount the derailleur to the hanger.  The frame mount threads are coarse enough that they printed successfully for me.