Scrap Durasteel is a new crafting material in LEGO Fortnite that became available with the May 3rd Star Wars update, v29.40. As part of the patch, many classics from the franchise made their way into LEGO Fortnite, and Scrap Durasteel is essential for crafting them.
How to get Plastoid, Durasteel and Scrap Durasteel in LEGO Fortnite Star Wars!
More specifically, most Star Wars x LEGO Fortnite items, such as the Bowcaster, DL-44, E-11, and the Thermal Detonator, require you to have Durasteel in your inventory, and the fastest way to obtain that material is by obtaining Scrap Durasteel.
You can make Durasteel from leftover Durasteel. This is how you find it in LEGO Fortnite.
To get Scrap Durasteel in LEGO Fortnite, you'll need to visit Galactic Empire bases. I got most of my Scrap Durasteel after fighting Stormtroopers guarding Galactic Empire bases, but you can also get Scrap Durasteel by destroying crashed ships and Star Wars buildings.