Bricks

Bricks are a currency originating in Scrap Clicker 2 and were later introduced in ScrapTD. In Scrap Clicker 2 they are used to buy some upgrades while in ScrapTD they are used for buying and upgrading barrels and defenses.

In Scrap Clicker 2
Unlocked at x15 Stars, Bricks are passively accumulated. Starting at 1 per second, production can be permanently and repeatedly upgraded in the following ways with all multipliers stacking:
 * Upgrading overall Star multiplier: x4 multiplier
 * Spending levels: multiplier *
 * Upgrading "More Bricks" upgrade by spending Bricks: x1.25 multiplier
 * (40+ Stars) Purchasing specific upgrades in the Skill Tree: multiplier
 * (105+ Stars) Upgrading the scrapyard v4: x1.5 multiplier/level

* Levels required increase by 1 every time production is increased by this method, however this can be lowered by purchasing the appropriate upgrades in the Skill Tree.

Upgrades
More Steel Beams' cost multiplies by 8 with each level ,all other upgrade's cost is x4 per level.

Brick Multipliers
Once the player has achieved the top Golden Scrap Multiplier, they begin earning Brick Multipliers (if they are above the Barrel 103):