The Necron Monolith is a huge floating tank and transport vessel for the skeletal Necron faction in the tabletop war game Warhammer 40,000. As in many miniature war games, half the fun is in painting the units, which come unfinished upon purchase. While you should use colours that match the rest of your Necron army, your Necron Monolith will look particularly impressive with a coat of colour-shifting paint that allows it to sparkle between purple and green when viewed from different angles.
Mask over any parts of the model that you don't want painted. If you're using lights on the Monolith, be sure to cover all of these before painting.
Spray a coat of primer over the entire surface of the Monolith to begin. Follow this with several coats of colour-shifting paint, waiting for each to dry before spraying the next. The exact number of coats you apply is up to you, though the colour-shift effect becomes more dramatic with each coat you add. Spray a gloss coat to finish the base colour.
Paint the arches with a colour that complements the rest of your Necron army. Gold is a good colour choice, contrasting well with the dark purple-green of the body, as long as your other Necrons have gold in their uniforms as well. Paint the gauss guns the same colour as the weaponry used by your Necron forces. Define the edges of the body panels with a black pen liner and paint the base in the colours you use for ground foliage.