A pack of thick crayons any shape (I like the Mellissa and Doug set. 5 dollars on amazon and have lasted Theo very long)
Although the crayons are thick, they are training those little wrists, hands and finger muscles for greatness. Open ended coloring is something I love for young children: it’s child lead, therapeutic, they make whatever they desire (could also relate to emotional development).
Little do they know they are actually doing some great things for those little hand muscles (and brains)!
Theo is a fan- sometimes I will switch them out for markers and sometimes even chalk! Providing the child with a variety of materials will keep them longer and give those muscles a bunch of different sizes and shapes to learn to work with.
You can switch up the things they are coloring too-there’s more than paper to use as a muse-boxes, canvas’, poster boards, etc-be creative and open!
The older the children get, it becomes a great opportunity to teach grip on writing utensils (don’t expect this to be anywhere near correct at first!!-the first step is to train the muscles and make them strong to hold their utensils in the future.) You may even have to model how to use a crayon/marker etc. at first!