Everything about eyeglass rivets, eyeglass pins:

What are eyeglass rivets? 

They are small metal pins usually appearing on temples and frame fronts, for mounting hinges and temples or hinges and fronts together.

What materials and sizes are available for them usually ?

They are usually made of nickel or soft stainless steel. Size from 2.0mm to 10.0mm length, diameter from 0.5mm to 2.0mm. Custom work is available as well at MOQ: 10,000 pieces as per your size.

How many types of eyeglass rivets are there available ? 

According to the different structures, there are single rivet and double rivets, two types mainly. For single rivets, there is only single pin stem available, while for double rivets, two pins stems are attached together under the small metal plaquette so that when mounting  universal hinges which have two holes, it only needs to be done in one time instead of two times seperately.

How could I mount hinges onto temples or fronts by rivets ? What tool do I need ?

One small punching machine is enough for doing it,and it's easy. Firstly, installing suitable punching head into punching machine, secondly, put the temples,hinges together and pierce them in one straight line by rivets, put them vertically below the puncher head, press the machine's handle down, ok, the rivets end has been mounted well already.