Pentacle and Bell

Pentacle

The pentacle is usually a flat piece of brass, gold, silver, wood, wax or clay, inscribed with certain symbols.  The most common, and indeed the only necessary one, is the pentagram, the five-pointed star which has been used in magic for millenia.  

The Pentacle was "borrowed" from ceremonial magic. In this ancient art it was often an instrument of protection, or a tool used to evoke spirits.  In Wicca, the pentacle represents the element of Earth and is a convenient tool upon which to place amulets, charms or other objects to be ritually consecrated.  It is sometimes used to summon the Gods and Goddesses.

Pentacles are also hung over doors and windows to act as protective devices, or are ritually manipulated to draw money owing to the pentacle's Earth associations.

Bell

The bell is a ritual instrument of incredible antiquity.  Ringing a bell unleashes vibrations which have powerful effects according to its volume, tone, and material construction.  

The bell is a feminine symbol and so often used to invoke the Goddess in ritual.  It is also rung to ward off evil spells and spirits, to halt storms, or to invoke good energies.  Placed in cupboards or hung on the door, it guards the home.  Bells are sometimes rung out in ritual to mark various sections and to signal a spell's beginning or end.  

Any type of bell can be used.

Taken from, "Wicca, A Guide for the Solitary Practitioner" by Scott Cunningham