This is a stackable and rotatable riser/support that is compatible with various wooden train sets. I designed my own as i found it hard to find something similar that was stackable, rotatable, and acted as a tunnel.

I have tested the widest carts i have and they are all able to go through the tunnel portion.

I print upside down with support.

Update December 2024: 
Some users have mentioned compatibility issues with IKEA train sets. I have made a slight update to the model and tested with a fresh pack from IKEA and it should fit much better now.