Mark out your perimeter with this pack of three OO scale ready to paint concrete wall, 3D printed in grey ABS-like resin and supplied unpainted.
Sectional design lets you build runs to any length, with crisp surface texture taking a wash beautifully.
Paint in the right brick or stone tones, weather with a wash, then add a few scenic tufts or a creeping plant at the base for naturalised character.
Build the perimeter your layout has been missing.