Red Bricks in LEGO Batman are used modify the look of your characters' suits. There are 23 of them hidden across the game, and some can only be obtained via secrets in story missions.
Below you'll find the location and a short comprehensive guide of where to find each one.
You'll find the Red Brick for this level just after building the catapult. Follow the grapple interactable all the way around to the right, until you reach a drop down to a vent opening. Head inside to the puzzle room, and place the nearby books onto the pressure plates. Finally, use both characters to depress the last two plates, and the brick will be revealed.
Nautical - Docks
You'll find the Red Brick for this level hidden in a room near the battering ram. Simply grapple onto the roof and drop down inside to retrieve the Red Brick
Filthy Rich - Iceberg Lounge
You'll need to solve a combination lock to get this Red Brick. The code for this lock can be found in the room to the right of the lock, behind the bar. It's very easy to spot, notably due to a lady who walks out from it in a black dress during a short cutscene. Inspect the item there and you'll receive two of the three numbers needed for the lock.
Toxic Waste - ACE Chemicals
After progressing past the room with the giant purple vat of chemicals, you'll notice a room off to the right with a Red Brick stuck inside of the pipes. Simple get Jim Gordon to use his goo gun on the yellow holes, and it will force the brick out onto the other side.
Feline - Shreck's Hardware Store
You'll need to play a maze mini-game to win this Red Brick. You'll find the game below the gadget store, and will need to connect the wire from the pad in order to turn it on. The goal is to gugide the cat to the exit by standing on the directional pads to move it. Hitting the orange cat at any point will put you back to the start, so be careful!
Artist - Flugelheim Art Gallery
In order to grab this Red Brick, be wary of the security room. Instead of just hitting the button with Catwoman's cat and leaving, instead make your way up above the screen, and follow the platforms to the catflap in the top corner of the room. This will lead you to the red brick on the other side.
Showbiz - The Big Dukeroo
In order to grab this Red Brick, take note of the open interior apartment just above the second parade float, to the right of it. Send Catwoman in by cutting the glass, and position the TV just halfway in the room so that her cat can use it to jump into the vent on the left of the room. Follow this vent all the way through, and you'll find the brick on the other side!
Clown - Haly's Circus
In order to grab this Red Brick, make sure to NOT take out the enemies in the first combat encounter. Doing so will mean you'll need to restart the mission to get this brick. In order to obtain it, simply stand on the yellow pressure pad of the machine, which will reveal 3 targets. Have Robin hit the targets at once with his gadget, and you'll unlock the brick!
Power Plant - Gotham Water & Power
In order to grab this Red Brick, head to the back left corner when you spawn in to the mission. Pry the door open as Robin, and head inside. You'll need to first attach a line with Robin's gadget from the blue battery cell on the center console to the fuse box on the right side of the room.
Then, use his staff on the left side of the room to shut the center hatch. While shut, switch to Batman, and you should glide up to the ceiling. Finally, switch back to Robin and lower the hatch again so you can switch to Batman one final time to retrieve this brick.
Flower Power - Botanical Gardens
In order to grab this Red Brick, you'll need to take two of the three flower pots on the right side of the room, and place them in the correct order within the center console. For me, it was red first, green second. It may be different for you.
Fire Breather - Botanical Gardens
In order to grab this Red Brick, set all of the planet projections specifically to the color red. Doing so will open up the center planet, and reward you with the brick.
Ice Age - Observatory
In order to grab this Red Brick, use Batgirl's to open up the three switches on the back side of the arena. Then, use Nightwing's primary ability to hit all three switches at once. When done correctly, the brick will be released.
Bats - Shadow Over Gotham
In order to grab this Red Brick, take note of the garbage truck on your left when returning back up to the street. You will need to use both Nightwing and Batgirl's abilities in order to move the truck into position and use it as a shield from the enemy tumblers. Doing so successfully will let you grab the brick.
Bat-Mite Shop Red Bricks
All Red Bricks below can ONLY be purchased from Bat-Mite's shop. They spawn in the center pedestal randomly each time you visit, and all require studs in order to purchase.
Name:
Stud Price:
Beauty
50,000
GCPD
30,000
Magic
35,000
Groovy
25,000
Glitch
25,000
Futuristic
25,000
Festive
25,000
Sporty
20,000
Construction
15,000
Conclusion
There you have it! We hope this guide helps you out as you continue to tackle the many criminals infesting the streets of Gotham!