Created a simple insert and holder for the trains in Irish Gauge that you can just pull out of the box and use at the table. Also allows the game to be stored vertically and the game board keeps the trains where they belong. The train well has small rounded corners inside to help getting the trains out.

This is my first design so I am sure you can make tweaks to improve it.

Printed at .2mm with 20% infill, but you could probably go less.