Cut mozzarella into 3/4-inch cubes. Slice each nectarine into 6 wedges, and cut each wedge in half (for a total of 36 pieces; you'll have a few extra). Set aside.
Skewer 2 cubes mozzarella and 2 pieces nectarine per wooden pick; place on a serving platter. Drizzle with pesto (thin with a little olive oil, if needed), and serve.
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