A variety of media,lolly sticks, feathers, wood shavings, paper straws, crumbly stuff, solid stuff, flexible stuff etc. I use the 'Can-do' pots for smaller items ( fine motor, pincer skill development) such as sequins, lentils, small material offcuts, cut up straws, ( check for choking), the children are happy just closing and opening them before they are even interested in what's inside.

. Collage pictures, again they will explore the glue first, dripping it and 'painting with it on the paper.
Get down from off tables, large tarpaulin cover on the floor, lots of junk, boxes, cardboard rolls, different coloured textured paper / material and a few glue pots, masking tape ( easy to tear instead of cuttting). They can make individual models or just add to a large 'group' one, although this will mainly be done in 'parallel' play.
Another one is shredded paper, either damp so it can be moulded into balls, mounds etc or dry with boxes available to stick the paper to. ( great fun, or not, when it gets stuck to their fingers and they try to problem solve how to get it off their fingers and to stay on the box

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Sensory smelly pictures, use any means to 'hold a scent', small bits of sponge, food stuff - ie: lemon, onion, coffee, etc ( strong smells) pot pourri.
It's the exploration, cause and effect discovery rather than the end product at this age, plus a little bit of problem solving, how to stick things together, spacial awareness, how much to fit onto one side of a box, one peice of paper etc.
Peggy