is it possible to build? that would be very nice
Yes, you can use Scrap Metal to build, their main source from Traps, which you'll need to break to attain. If my memory serves me right, each use consumes 20% of the item's usage, being able to place 5 Scrap Piles if the Scrap is at 100-81%. Due to their limited charges, their main uses are to create a bridge over a small gap that may prove dangerous or to create an extension of a platform which will allow you to jump over a previously impossible gap. They're also a common currency used when trading with other Survivors, worth 8 Trade Value at 100-88%(Really, it's 87.5% but the game displays rounded percentages instead). Also, it's important to note that once you place them, you'll not get refunded when breaking them. The button to place them is Left-Click when having it in your Main Hand.
Also, here's a quick tip: When breaking traps, you can break the block directly under it to break it instantly. This is especially useful if a Trap is placed on sand, gravel, soil, a trash pile, or a scrap pile. Regardless of the material(unless it's a heat-resistant alloy or steel tile), this method is always faster than breaking it directly. This method is also a requirement to break Coils and Bear Traps.