This is what remains of Skif's 2S1 Gvozdika (Carnation) SPG, with resin wheels from Masterclub, a gun tube from Barrel Depot, photo-etch from Eduard, Fruilmodel metal tracks, and plenty of scratch-built details.
I used the hairspray technique for the majority of the chipping effects. I used Tamiya acrylics for the airbrushing and Vallejo for all the brush-painting. I copied some online photos of Russian graffiti and painted them on the back of the tank using thin layers of Vallejo paints.
This topside view shows off the concrete base. I used different thicknesses of styrene sheets to achieve a slightly uneven appearance. I stippled both Mr. Surfacer 500 and 1000 on different slabs for an inconsistent texture. I sprinkled a pinch of plaster on the still-wet Mr. Surfacer to further diversify the texture.
I painted the concrete using Tamiya acrylics. I focused on painting a gradient of dark gray to light gray from one corner of each slab to the opposite. I applied several layers of washes, and some Vallejo white and tan paints were applied in random spots using a sponge to further simulate texture. Finally, I added some static grass and weeds from Busch into the cracks.
I had a lot of fun with the graffiti. I lack the disrespect for public and private property to actually do it in real life, so I had a go at it on the back of this tank. I figured the back would be the best place for sneaky hooligans to tag something without being noticed. Here, you can also see the wire contraption that I soldered out of brass rod. It's much more robust than the kit part, and it's closer to the correct size... however there are some nasty gaps at the attachment points that I failed to fill.
I appreciate all comments and feedback. Thanks for looking!