Answer:
as I know about barometer consist of a mercury .
it can be made with a clean ,dry, thick walled glass tube of about one metre long .
the working mechanism can be given by:
when there is air pressure the mercury in the glass goes against the air pressure to balance itself .
If the weight of mercury is less than atmospheric pressure then the mercury will rise upwards and vice versa.
I think no need to explain the parts u can do it your self as it consist of testube and mercury as main components.if u want the explanation then use search engines to reshearch.
hope this helped you
comment if got any confusion .
