if you are strengthening the muscles in his fingers:
Playdough, clay,origami (folding paper)-airplanes-origami ornaments for the tree-my brother did this as a small child. check out a book form the library or get a book in your amazon shopping cart.
other ideas: Painting, finger painting,
tub paints if child still takes baths. sidewalk chalk
sand-tables-
rice tubs-
learing keyboard typing on the puter or a musical keyboard
or guitar
bake! make cookies- let child use the rolling pin and the cookie cutters