Filter
Filters can be made from mechanical components.  They will do very similar things to electric filters.  Most especially, mechanical filters can be wave filters.  That is, they can block some frequencies and pass others.  Because of this, electric filters are sometimes made by first making a mechanical filter.  The electric wave is turned into a mechanical movement, then passed through the filter, then turned back in to an electric wave.  This kind of filter is often made from quartz crystals.