Chodník čtverce (12,7 x 12,7 mm)

A paving grid with a 12.7 millimeter edge

The scribed sheet of white polystyrene carries a regular net of squares with a side of 12.7 mm. The grooves run across the whole 15 x 30 cm format, so one sheet yields a continuous sidewalk with offcuts left over for bays and corners.

The size of the square decides which scale the surface suits. In 1:24 it works out at a tile with a 30 cm edge, in 1:35 roughly 44 cm and in 1:48 about 61 cm, that is, the large concrete panels laid in courtyards, on ramps and on station platforms. In small scales, by contrast, the grid reads as a surface made up of large-format slabs.

Where the scribed surface fits

• sidewalks and curb strips along buildings,
• the courtyards of workshops, depots and loading ramps,
• the floors of halls where the joint pattern should show,
• the base of a display-case scene cut to size.

Cutting and painting

Polystyrene is divided by scoring it with a knife and snapping it over the edge of a table; the groove of the grid serves as a guide for a straight break. Joints are held by solvent cement for plastics, and the joints can be deepened with a scriber or the point of a needle. Before spraying it is enough to wash and degrease the surface; the concrete is then laid in with a gray primer and the differences between individual tiles are painted in dry with a fine brush, so that the hard standing does not look uniform. Cracks and chipped corners call for no more than the point of a scalpel run along a ruler and light pressure, because one millimeter of material breaks off without resistance.

It is worth backing the edge of the surface with a thin strip of plastic so that the sidewalk stands above the terrain and casts a shadow of its own; the transition to the soil is then covered by a mixture of sand and crushed pigment.