The Scavenger skill has the chance to drop random items of your choice. By default it includes scrap and metal fragments. These are just items I wrote in to get you started. You can remove these items and add your own custom list of items. To do this you will need to manually edit the config file (in game admin panel doesn't have this ability yet).

When you open the config file look for this section:

"scavChanceList": {
      "0": {
        "shortname": "scrap",
        "amount": 1,
        "maxamount": 10,
        "requiredlevel": 1
      },
      "1": {
        "shortname": "metal.fragments",
        "amount": 1,
        "maxamount": 10,
        "requiredlevel": 5
      }
}

You can edit the items in the list by changing the shortname to the item you want and control the amount of items that drop by changing the amount. You can also set a max amount for each item so it will never drop more than that amount no matter what the skill level. To add more items to this list you need to add a new entry like this:

"0": {  // Next number in the list
  "shortname": "itemshortname", // Shortname of the item
  "amount": 1, // Amount to drop
  "maxamount": 10, // Max Amount at one time
  "requiredlevel": 1 // Required skill level to get drop
},

Make sure you continue to increase the next number and do not have any repeating numbers in the list. You can add as many items as you wish. The Scavenger skill will randomly choose one of the items in this list to drop when the skill activates while looting.