Draw a long, thin vertical rectangle
Round the top end slightly
Draw a larger bulb at the bottom
Add a narrow tube connecting the bulb to the body
Draw a thin inner line inside the tube
Extend the inner line upward to show the mercury level
Add small tick marks along one side of the body
Make some tick marks longer for measurement intervals
Label the scale if needed
Outline the thermometer neatly
Erase extra guide lines
Shade the bulb and mercury line lightly