The left hand side of the layout will disappear into a crude tunnel entrance built from huge wooden supports while the tunnel interior will be defined with some wooden shuttering.
The first image shows the start of the wooden shuttering. Built from scrap wood and DAS modelling clay over some 3mm thick plastic card the walls have been detailed with plastic card and florists wire.
The wooden tunnel entrance was inspired by a mine entrance I found on the internet and built from some spare balsawood blocks. The entrance has been scaled to accept the narrow gauge engines (just).
The final image for this post shows the first parts built (but not glued down). I still need to determine how far around the entrance needs to come on the layout and build the right hand shuttering and paint them.....