According to Amanda Morgan of the Not Just Cute Podcast https://notjustcute.com/podcast/ "before we ever put a pencil in a child's hands, those hands should dig, climb, press, pull, squish, twist and pinch in a wide array of environments and with a variety of materials".
Indeed when you look at the difference in bone structure of a 3 year old and a 7 year old child as seen in these x-rays, we begin to realise little hands are still unfolding and forming.
In general, control of the muscles progresses outwards from the center of the body. For example, children usually develop the muscles of their trunks and shoulders earlier than their legs and feet which are further from the center of their bodies. Therefore, a preschool child’s hands are still developing. Children need to be given opportunities to perform a range of tasks to develop their fine motor skills and strengthen the muscles in their hands, fingers, and wrists as they continue to grow https://www.childcareed.com/a/let-them-play-supporting-children-s-natural-development.html
As you can see by the photographs, the children in our setting engage in a whole range of activities that are beneficial to strengthening fingers and hands.
A favourite with nearly all the children is playdough which is a fantastic malleable material that not only provides actions such as squishing, pressing and rolling but also provides limitless opportunities for creativity and exploration.
Malleable materials are a great way to improve children's fine motor skills, strengthen fingers and in turn support the development of hand/eye coordination. Even in Reception classes playdough is still used to strengthen young hands https://www.spreadthehappiness.co.uk/dough-disco/ or look at YouTube for ideas e.g. https://www.youtube.com/watch?v=BOLR3pQt8zg
There is a definite developmental path to writing which most children follow but we can explore that at a later date....for now enjoy making sandcastles, creating playdough cakes, pouring, scooping, mixing paints and creating bubbles in the water.