Craft shops are worth a rummage around, particularly the beads and jewellry section. Beads make useful pots and urns & some of decorative elements can be used as wall features, signs etc. The papercraft section also turns up useful odds and ends. Sacks are easy to make with greenstuff etc. Metal foil makes for awnings etc, either lead (off wine bottle closures) or aluminium (the thicker grade, used eg for take aways or for sealing off cans of instant coffee etc).