The figures are from, the now defunct, Odemars - as usual in 1/72 (or 25mm) scale. They were cleaned with a fresh nº11 blade, primed with white glue diluted with water (to give the paint something to stick to, since they're made of soft plastic), and also received a white coat to turn the colours more vivid. The flesh was painted with a mix of Vallejo paints and "washed" with diluted oil paint to give depth.
While doing some research about the Nativity, I came across a painting by Giorgione that served as main inspiration:
To create the base, I used balsa wood and styrofoam cut with a hot-wire cutter and a shaving razor.