N Scale Tunnel Liners

This printable is a set of modular tunnel liners for N scale - effectively they make a solid tunnel that allows to easily build scenery over them without causing damage to track or tunnel.
The liners have been designed to work with Woodland Scenics N scale cast plaster single track tunnel portals. The size of the portals is enough that Viessmann hidden track catenary (brass strip) can be mounted using separate mounting blocks.
In practice these portals and liners are large enough to take long (scale 27m) coaches and US double-stack container cars (without catenary...).
The liners are designed to accept embossed brick/stone card lining of you wish or simply be painted - 1 photo shows both of these approaches. You'll see in the other photos that I've used dark gray PLA for some prints - I thought this would save me painting but the PLA came out shiny and I found that I needed to paint it anyway.
The liners are in two types - straight and angled - and I've made combinations fit curve