To facilitate the manufacture with an extremely small size by using, as one of materials, a granular body having a specified particle size when dispersed at random into a base material consisting of the other material.

One of materials is formed of a granular body having a particle size of 0.2-10mm, preferably, 0.2-3mm when dispersed at random into a base material 2 formed of the other material. The dispersed state of the granular body to the base material can be attained to a degree sufficient for a desired lap finishing by a simple mixing operation, and a device for arranging island-like dots in a precise ordered manner as it necessarily takes much cost and time is not required. The base material may be formed of a binder having a thermosetting resin as substrate, but it is preferably formed of a metal material covered with this binder. The granular body 1 is formed a metal material covered with a thermosetting resin binder.