At Salute 2017 I bought two pillbox kits from Sally 4th. The Type 22 pillbox was assembled and painted last year. I decided to assemble the Type 24 as a concrete box, so covered the outside with a thin layer of Milliput. If you went to Colours via Reading, you might have noticed a similar box near Thatcham station.
I used Rustoleum Rust effect spray to provide some texture. I used masking tape to prevent the roof from sticking to the walls. The metallic effect paint was then covered with Halfords grey spray paint.
The final base colour was Army Painter Stone Golem acrylic, brush painted over the grey. This was then washed with first with Citadel Nuln Oil followed by Citadel Agrax Earthshade. It was then dry brushed with Citadel Terminatus Stone.
The door still needs to be painted.
Detail of the texture.
The roof texture.