Stringing beads is a great fine motor activity. You can also mix different facets in by getting shaped beads, colored beads, and/or letter beads.
The activity is rather straight forward. You buy beads. You buy some sort of string. You string beads.
I make jewelry, so I was very intent on buying supplies inexpensively. Honestly, if I had to do it over again, I would get a kit from Melissa and Doug. They are great quality and the price in the end is very similar.
Melissa & Doug Deluxe Wooden 27-Piece Lacing Beads in a Box