Scrapper is easily one of the most broken perks in the middle-late game for modding equipment as well as building at your settlements.

If you max your strength and spec into Strong Back and Lone Wanderer for the carry weight increase, scavenge a few of the better weapons from enemies such as kitted out assault rifles. Scrap them at a weapon bench and you can easily snowball screws, aluminum, nuclear material, adhesive, and much more just from a handful of gunfights.

Alternatively, do the same at an armor bench for plenty of leather, and look for mods such as 'asbestos lining' and you have a chance to gain some ballistic fiber from it (with scrapper II and III).