Arena Parts:
Win in the arena and get parts. Each time you win a part, you are notified via mail. 

Part Name - Part Type - How to Get it 

CWM-S60-10 - Back Unit - Win your first victory 
MGP-VE905 - Generator - Achieve D ranking 
CWGG-GR-12 - Arm Unit Right - Achieve C ranking 
CWC-SLU-64 - Back Unit - Achieve B ranking 
CLR-00-MAK - Legs - Achieve A ranking 
VREX-WS-1 - FCS - Achieve 35th ranking overall 
OP-E-LAI - Optional Part - Achieve 15th ranking overall 
CAW-DC-03 -Weapon Arms - Defeat Ace, the number one pilot 

Parts Found in Missions: 

Part Name - Part Type - Mission 

CHD-04-YIV - Head Defend - Naire Bridge 
MEBT-OX/MB - Extension - Rescue the Survey Team 
MWR-M/45 - Back Unit - Safeguard Water Supply 
MWG-SBZ/24 - Arm Unit Right - Recover Ship Cargo 
MWI-DD/20 - Inside - Defend Water Processors 
MEST-MX/CROW - Extension - Disable Pulse Generators 
MRL-SS/SPHERE - Back Unit - Protect Crest Convoy 
KWB-MARS - Arm Unit Right - Destroy Massive Weapon 
CBT-FLEET - Booster - Destroy Massive MT 

Parts found by completing specific actions in missions: 

Note: You must complete Destroy Gun Emplacements in less than two minutes and collect at least an overall A ranking to reach Distract Union Defenses, where you get the MWG-KARASAWA. Similarly, you must destroy all enemies and have at least an overall B rank when starting the Defend Water Processors to reach Eliminate the Bombers, where you collect the KWS-ES/MIRROR. 

Part Name - Part Type - Action 

MLH-MX/VOLAR - Legs - Gain a rank of A or higher in AC Test 1. 
KWG-HZL30 - Arm Unit Left - Destroy 2 or more monorails in Destroy Naire Bridge. 
RMR-ICICLE - Radiator - Keep all convoy units alive in Defend Personal Convoy. 
KWM-AD-50 - Back Unit - Don't get hit by a single missile in MT Training Exercise. 
MWG-XCB/75 - Arm Unit Right - Defeat enemy AC in Defend Ruglen Laboratory. 
CEEC-01-XSP2 - Extension - Beat Eradicate Life Forms without breaking more than 2 cylinders. 
CEBT-HEX - Extension - Keep transport vehicle alive in Safeguard Alloy Sample. 
KWX-OC-22 - Back Unit - Kill 20 or more enemies in Destroy Germ Canisters. 
WMG-KARASAWA - Arm Unit Right - Beat Destroy Gun Emplacements and Distract Union Defenses. 
KWS-ES/MIRROR - Arm Unit Left - Beat Defend Water Processors and Eliminate the Bombers. 
MCM-MX/002 - Core - Kill enemy AC unit in Defend Energy Reactor. 
MLB-MOONLIGHT Arm Unit Left Defeat largest enemy in Destroy Massive MT without using a consort. 
MWX-MX/STRING Back Unit Beat the game and save after winning. 
OP-INTENSIFY Optional Part Beat the game and save after winning. 


Parts gained from corporate points: 

Part Name - Part Type - Corporate Points Required 

MLL-MX/EDGE - Legs - 6 Mirage points 
MWGG-XCG/20 - Arm Unit Right - 9 Mirage points 
MLR-MM/PETAL - Legs - 12 Mirage points 
CAL-44-EAS - Arms - 8 Crest points 
CWX-LIC-10 - Back Unit - 13 Crest points 
CLF-D2-ROG - Legs - 17 Crest points 
OP-E-LAP - Optional Part - 10 Kisaragi points 

Drop parts:
Hold L1 + L2 + R1 + R2 + Triangle to drop your R arm weapon, Back Unit, and Inside parts. 
Hold L1 + L2 + R1 + R2 + L3 to drop Extension parts. 
Hold L1 + L2 + R1 + R2 + Circle to drop L arm weapons. 

Get Defeated AC Emblems:
View the Arena Menu and select a ranked AC that you have defeated. Once an AC's profile shows up and you see the AC and emblem press Start+Select at the same time. You should hear a noise if you did it correctly and you get the AC's emblem. 

First Person View:
Insert a memory card with saved game files from Armored Core 2 or Armored Core 2: Another Age. After saving and resuming in Armored Core 3 from that memory card, pause the game, then press L1 + R2 + X + Square + D-pad to get a first person view of the current screen. The screen will return to normal when the game is resumed.