This is my under-three category. Nothing here is small enough to swallow, nothing rolls under the sofa, and all of it survives being squeezed very hard by a 3 year old with strong opinions.
Homemade dough is the base of most of it. I make a double batch on a Sunday, split it into three colours, and it lives in the fridge in old yoghurt pots for a couple of weeks.
The rest are variations on the same feeling: salt poured onto glue, wool pressed under warm soapy water, a bar of soap softening under a lolly stick.
These are also the trays I can leave out. They get picked up, abandoned, and picked up again between other things, which is exactly what I want on a slow day at home.
Tip
Natural colours work beautifully in dough: turmeric for yellow, beetroot powder for pink, spirulina for green. And a squeeze of hand lotion into the dough makes it silky enough that adults want a piece too.