These are for lining an N scale model train tunnel. There are two types of liner: -

• A simple straight liner (STL file has 6 of these)
• An angled liner (STL File has 12 of these)

They are designed to work with Woodland Scenics cast plaster tunnel mouths and allow plenty of clearance for UK and European models, even having enough room for catenary (you can see Viessmann brass catenary strip in the right hand tunnel in one of the photos.  This is held in place with the 'Tunnel Mount Strip Holder' which has to be stuck at the top of the end segments, maybe intermediate ones too, if you have a long tunnel liner.

The clearance allows you various options for installation: -

• You can print the segments in an appropriate colour and simply install them.
• You can paint the interior, say matt black as in my photo.
• Or you can line them with paper/card/plastic material to represent whatever interior you prefer - again, see the photos.

As these are self-supporting, you can test fit and run your trains through before fixing in place. If your tunnels are on a corner you will need combinations of straight and angled segments to complete the curve at the right radius.

When I'm happy with my fit, I typically mark the outside of each segment and then stick them all together to make a single piece.  Note that if you take care to ensure you use sufficient glue, you can make the joints water tight and that is a big benefit when it comes to scenery fitting.

Another option is to install the assembled segments and rather than fixing them to the baseboard, fix them to the scenery so that the whole tunnel can be lifted off.  This wouldn't work with catenary, of course.

Note that the segments are printed upside down to avoid the need for any support structure and therefore usually print very cleanly.