Using ordinary poster paint and a very small amount of PVA glue
(just so that the paint doesn't flake!!)
Add a few drops of essence to each colour paint - you could colour associate it if you wanted to. (orange aroma with orange paint, Apple with green paint etc.)
Paint 'thick' patches on to seperate pieces of card and leave it to dry.
Hang the cards up as a 'free play' activity or have as a table activity and see if the children can scratch the paint and see what they can smell !
