Complex modification rules for Karabiner Elements to map shift keys to parentheses. Use the URL in the comment to import easily.

shift_to_parentheses.json

{
  "title": "Single-hit shift to parentheses",
  "rules": [
    {
      "description": "Map single-hit left shift to (",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "left_shift",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "to_if_alone": [
            {
              "key_code": "9",
              "modifiers": ["left_shift"]
            }
          ],
          "to": [
            {
              "key_code": "left_shift"
            }
          ]
        }
      ]
    },
    {
      "description": "Map single-hit right shift to )",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "right_shift",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "to_if_alone": [
            {
              "key_code": "0",
              "modifiers": ["right_shift"]
            }
          ],
          "to": [
            {
              "key_code": "right_shift"
            }
          ]
        }
      ]
    }
  ]
}