Half of the fun of Knights of the Old Republic is developing your party members in your own individual way, and I encourage you to do so. Nonetheless, I am providing development guides for every playable character as I have figured out ways to develop a very powerful party, and if you're the type of person, like me, who enjoys a Dungeons & Dragons type battle system; then even if you don't follow the guides, they may hopefully at least provide interesting reading and food for thought...
T3-M4 is Level 3 when he joins your party.
At Level 3, T3 has the following Attributes:
At Level 20 I have the following Attributes:
I equip the following at endgame:
Universal Computer Interface - Superior Targeting Computer (This is how he has the Feat Weapon Specialization: Blaster Pistol) - Advanced Computer Tool - Baragwin Flame Thrower - Composite Heavy Plating - Baragwin Stun Ray - Baragwin Droid Shield - Mandalorian Heavy Pistol (x2)
At Level 20, I have T3-M3 with the following Feats:
Click here for lists of Droid equipment in KOTOR.
At Level 3, T3-M4 has the following Skills:
Character Development Home
Player Character Guide