It does not have to be tweed does it. I have a plethora of waistcoats, but not one is tweed.

A 5 button navy blue - barathea wool,
A 5 button black - barathea wool,
A 5 button forest green - barathea wool,
A 5 button buff - suede,
A 5 button red - melton wool,

A 6 button black - barathea wool - round neck,

A 3 button navy blue - barathea wool,
A 3 button forest green - barathea wool,
A 3 button black - barathea wool,
A 3 button white - maracella cotton.