(all images from http://www.museum.rbi.org.in/c-ancient.html)
Issued initially by merchant Guilds and later by States, the coins represented a trade currency belonging to a period of intensive trade activity and urban development. They are broadly classified into two periods : the first period (attributed to the Janapadas or small local states) and the second period (attributed to the Imperial Mauryan period). The motifs found on these coins were mostly drawn from nature like the sun, various animal motifs, trees, hills etc. and some were geometrical symbols. (http://www.museum.rbi.org.in/c-ancient.html)
The process of making coins went as follows:
• Metal was first melted in crucibles and purified with Alkaliea.
• It was beaten into sheets on an anvil with a hammer.
• Sheets were later cut into pieces with clippers to a particular weight.
• Finally the pieces were stamped with dies or punches having symbols. (http://www.geocities.com/dakshina_kan_pa/art7/coins.htm)