Schematics

Schematics are the blue-prints for custom built Weapons in Fallout 3. After finding a Schematic you'll need to find 4 items and a Work Bench required to build it. Finding more than one of the same Schematic will improve the weapon's damage by 10%, so by finding 3 or 4 copies of the same schematic could improve it's damage by 30 or 40%.

[edit] List of Schematics