I have updated the design and it is tested and fully compatible. BUT - it needs some force since the dimensions of joints aren't exactly like original duplo. I will update this later, sorry for any inconvinience.
See images above.
A cross track compatible with Lego Duplo train tracks. Designed for easy printing without supports. I have also attached my SketchUp file with both designs if someone wants to remix. If you print one, please share your make. Thanks!
Two version are available - one with smooth finish, second with traditional threads on the top.
Just print with a decent infill (15%) and use.