Although I am not working now, I used to be a special education teacher. I too would have his fine motor checked out by an OT....can't hurt.
And in the meantime over the summer could you become real arts and crafty? All the work in arts and crafts can strengthen those muscles....play dough (or other clay and dough crafts), collages, painting, cutting, etc. just fun ways to work the fine motor. Michaels and even Oriental Trading Co have kits and supplies. For my gifted kid when we homeschooled we might learn about a culture in historical context and their artwork and then do our own....so cutting up small squares and triangles of construction paper and glueing down our own mosaics was part of history but I was also working on some OT goals. I had fun too.
