Washing line and clothes pegs
One Hundred ToysGive them eyes and you have a crocodile; grip a lolly stick to make an aeroplane; put ten on a coat hanger for a readymade abacus. If you need inspiration, Pinterest - my sworn enemy - is your friend. Just don't get sucked into creating elaborate activities needing tons of prep. Keep it simple.
Combine with a washing line for best results. A three-year-old can pair socks, a preschooler has fun ordering numbers and letters (and working out which one is missing). Everyone loves pegging things.
Brilliant for fine motor skills, the simple act of opening and then releasing a peg requires plenty of strength and co-ordination. The pincer and tripod grips develop; pen control improves.
What's not to like?