Blue Iron Door
Press & hold Activate to lock it or set a combination. Upgrade & repair with a construction tool using the secondary action.
Upgrade path
Hit a placed block with a stone axe, claw hammer or nail gun while carrying the material of the next step: 6 hits per upgrade.
Crafting
Craft at Backpack · makes 1
Crafted as Iron Door: pick this one of its variants when you place it.
Forged Iron× 10
Harvest drops
Iron× 4-10
Taken apart with a harvesting tool (axe, pickaxe, shovel), before perks and tool bonuses.
Drops when destroyed
- Iron× 10
When it collapses
Falling, it leaves 
Scrap Metal Pile (75% of the time) where it lands.
Where to find (13 POIs)
Pop-N-Pills Factory (tier 5), HSP Logistics (tier 4), Town Hall (tier 4), 4 Ever Video (tier 3), Bob's Boars & Carl's Corn (tier 3), Hybrid Energy Substation #1 (tier 3), Johnson's Warehouses (tier 3), Mamma Pizza (tier 3), Animal Hospital (tier 2), Hybrid Energy Substation #2 (tier 2), Hybrid Energy Substation #3 (tier 1), Construction Warehouse, County Line Substation.
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.