Manufacturing involves a full array of production from handicrafts to moulding iron and steel and stamping out plastic toys to assembling delicate computer components or space vehicles. In each of these processes, the common characteristics are the application of power, mass production of identical products and specialised labour in factory settings for the production of standardised commodities. Manufacturing may be done with modern power and machinery, or it may still be very primitive.

Why does moulding iron and steel and stamping out plastic toys to assembling delicate computer components is considered as secondary activity ?

Both 1 and 2

Secondary activities add value to natural resources by transforming raw materials into valuable products. Moulding iron and steel and stamping out plastic toys to assembling delicate computer components refers to transforming raw material into valuable products or value addition.