Abstract: A method and device enabling friction stir welding along non-linear joint lines or seams on either planar or non-planar surfaces are provided. The device features four roller clamps located on upper and lower pieces. It also contains a non-consumable tool with a profiled probed end that engages work pieces and follows along a non-linear or linear joint lines in order to achieve high-integrity friction stir welds. No special anvil is required and the device can be manually or automatically operated and controlled. Operating similarly to a conventional sewing machine, this device and process enable an operator or user to manually guide work pieces to be welded through a friction stir welding tool and allows for flexibility in the path of the weld and the types of material being welded.