5 ashtrays from Japan

Oli set of 5 stackable ashtrays of identical shape but in different colors (orange, lemon yellow, blue, black, khaki green). They are encircled with chromed metal and their body seems to me to be a kind of hard plastic (bakelite?). They were made in japan, there's a stamp underneath, and some still have the "japan" label. They are in good condition, but do not hide their age, probably from the 70s: a slight stake and fine scratches on the chrome, and in the notch to put a cigarette, the plastic has small gaps of the shiny colored layer. They measure 7 cm in diameter, 3 cm in height. The whole weighs a little less than 500g.