Little boys will love the idea of working like daddy in the garage and everyone will appreciate the fine motor workout you can get from matching nuts and bolts. This idea (and several more in the same post) from Counting Coconuts.
Weaving through a rainbow- Fun activity that encourages balance, motor planning, coordination and body awareness. Teacher read “A Rainbow of My Own” by Don Freeman to go with the activity. Great pic as well, can be a group activity
Place milk in shallow dish- add drops of food coloring. Now grab a *magic* toothpick. Just dip the end in dish soap & touch the milk with it. Colors instantly shoot out at lightning speed creating a wake of rainbows.