One lane is 8 cm long by 2 cm wide. A space is a double lane - 8 cm long by 4 cm wide.
The range ruler is split into five spaces. The important thing here is that the ruler is marked in segments of 8 cm.
Officially, passive weapons markers are 3.5 cm in diameter. The smoke markers are actually 4 cm in diameter.
Technicially though, the size does not really matter provided the marker can cover two lanes.
Debris markers are equilateral triangles of 3.5 cm per side. Again, like passive weapon markers they have to cover two lanes.
Sand markers are isoscles triangles with the larger sides being 7.5 cm in length and the base being 5.25 cm. Sand markers have to be able to cover 3 lanes in a single space.
Obstacles are rectangles 7 cm long by 5.5 cm wide. They have to cover 3 lanes across a single space.