Bricks

Bricks are an important resource you'll get since you're at 15 Stars. They give several bonuses which will help you getting Stars faster.

How to get them
You'll initially get 1 brick pr second (B/s) which can be upgraded through:

Getting a star -> x4 B/s

Leveling it up -> x2 B/s

Upgrades
There are seven upgrades which can be bought with bricks (they are infinite except for the 5th and 6th upgrade, which have a limit of level 100). Every Upgrade gets 4 times more expensive each time you buy it.

More Fragments: Gives +5% Fragments per level.

More Magnets: You'll have a chance of 1% per upgrade of getting a Magnet worth x3, x6, x9, etc. depending in the upgrade's level.

Cheaper Scrapyard: Reduces Scrapyard's price by 3/4 each time you upgrade this.

More Magnets II: Gives you +2% Magnets per level when you Level Up.

More Scrap: Gives you +1% chance per level of getting x2 Scrap.

More Magnets III: Gives you +1% chance when converting a barrel for Star Fragments.

More Bricks: Gives you x1.25 Bricks each time you upgrade it.