The engineer is a call back to the Tinker Gnomes of the Dragonlance world of Krynn and the Sky Gnomes of Mystara’s Serraine. These Tinkerers are scientists, and while their devices may not make sense to everyone, in their own warped mindset of fantasy physics, they work.
  As an engineer, you enjoy and have the talent for creating odd and intricate items. These items are more scientific than they are magical. And while they may have small magical components, those then fuel the machine aspect.

Keen Eye

  At the third level, you can tell find traps passively (Perception roll DC 12). On top of this, if you roll an Investigation roll of DC12 can learn how the trap works and how to disarm it. You may even re-arm the trap later.

Construct Iron Puppy

  As your mastery of the mechanical improves, you begin to experiment with creating autonomous constructs. At level 6 you can create a mechanical companion. During combat, you can command it to take action during your turns.
  During your next long rest, you can create what is known as an “Iron Pup.” You must use 3lbs of Materials and 7 tinker points to create a tiny construct in the shape of a mechanical puppy or other small land animal. It has mechanical lungs so it does require air to breathe. Only its creator can control it and it can’t be persuaded to go against a command its creator gives it.
  It can perform a few simple commands like fetching a given object, holding open a door, or flipping a switch. Other tasks can be negotiated with the GM. Only one construct can be active at a time.

Iron Puppy
AC: 13	HP: 15	Speed: 25 feet
Str: 8 (-1)	Dex: 8 (-1)	Con: 10 (-)
Int: 7 (-2)	Wis: 10 (-1)	Cha: 3 (-4)

Construct Upgrade

At 10^th Level, you can use a short or long rest to upgrade your Iron Puppy using 5 lbs of metal and 10 tinker points. It is now a medium construct and can take on one of two variants:

Iron Defender
AC: 18	HP: 30	Speed: 35 feet
Str: 15 (+2)	Dex: 8 (-1)	Con: 10 (-)
Int: 7 (-2)	Wis: 10 (-1)	Cha: 3 (-4)

  Immunities: poison damage, Psychic damage, disease,
  Resistance: Cold, Fire, Force, Radiant, and Necrotic damage.
  Vulnerability: Piercing and Lightning damage
  Bite Attack Melee Attack: +4 to Hit, Reach: 5 feet, One Target, Hit: 12 (2d6 + 4) piercing.
  Claw Attack Melee Attack: +4 to Hit, Reach: 5 feet, One Target, Hit: 10 (2d6+2) Slashing.
Commands:

• Protect – Construct protects you or another creature as a bonus action. When within 5ft, the selected creature’s AC increases by 2. When the creature moves, it follows as far as its movement speed will allow it. When another creature attacks the selected creature, the construct makes a bite attack as a reaction. When another creature disengages from the selected creature, the construct takes an attack of opportunity as well.
• Heal – Construct heals you or another creature for 1d8 + 2 hit points as an action (can be used twice per short rest). The defender must be within 5ft of the target and uses 5 of your tinker points.

Emotional Connection:
  If you are damaged, the construct stops its action to come to your aid and uses its reaction to either heal or bite your attacker.

or

Iron Hound
AC: 14	HP: 60	Speed: 55 feet
Str: 17 (+3)	Dex: 9 (-1)	Con: 20 (+5)
Int: 3 (-4)	Wis: 11 (-1)	Cha: 1 (-5)

  Immunities: poison damage, Psychic damage, disease,
  Resistance: Cold, Fire, Force, Radiant, and Necrotic damage.
  Vulnerability: Piercing and Lightning damage
  Bite Attack Melee Attack: +6 to Hit, Reach: 5 feet, One Target, Hit: 16 (3d6 + 4) piercing.
  Claw Attack Melee Attack: +6 to Hit, Reach: 5 feet, One Target, Hit: 12 (2d6+4) Slashing.
Commands:

• Attack – Construct attacks a target creature of choice. It deals both a claw and bite attack with an advantage if it doesn’t have to move to the target. It does not have an advantage if the hound has to move to attack, but still multi-attacks.
• Scout – Construct scouts ahead of you up to their movement speed before returning. Upon returning, it projects an image of what it saw using 5 of your tinker points.

Emotional Connection:
  If you are damaged, the construct stops its action to come to your aid and uses its reaction to both bites and claw your attacker.

As well as affecting the construct’s reaction in battle, emotional connection affects you (for either construct). If the construct is destroyed, you have a disadvantage on each proceeding roll equal to the number of days your construct was active. You also immediately lose as many tinkers’ points equal to the number of days they were active and cannot make a new construct until half of those days have passed.

Construct Update

At 14^th level, you may use a short or long rest to update your Upgraded Construct using 10 lbs of metal and 10 tinker points. Your construct takes on one of two variants:

Iron Bastion	(From Iron Defender)
AC: 20	HP: 60	Speed: 60 feet (30 Feet)
Str: 19 (+4)	Dex: 8 (-1)	Con: 18 (+4)
Int: 7 (-2)	Wis: 10 (-1)	Cha: 3 (-4)

  Immunities: poison damage, Psychic damage, disease,
  Resistance: Cold, Fire, Force, Radiant, and Necrotic damage.
  Vulnerability: Piercing and Lightning damage
  Bite Attack Melee Attack: +7 to Hit, Reach: 5 feet, One Target, Hit: 20 (4d6 + 4) piercing.
  Claw Attack Melee Attack: +7 to Hit, Reach: 5 feet, One Target, Hit: 14 (3d6+2) Slashing.
  1st Level Spell Slot: (Chosen at the time of the Update): The Bastion can use the spell as an action for 5 tinker points.
Commands:

• Protect – Construct protects you or another creature as a bonus action. When within 5ft, the selected creature’s AC increases by 2. When the creature moves, it follows as far as its movement speed will allow it. When another creature attacks the selected creature, the construct makes a bite attack as a reaction. When another creature disengages from the selected creature, the construct takes an attack of opportunity as well.
• Heal – Construct heals you or another creature for 1d8 + 2 hit points as an action (can be used twice per short rest). The defender must be within 5ft of the target and uses 5 of your tinker points.
• Change Form – For 15 tinker points, the construct increases in size to become a large creature of the same shape. It remains under your control but has its own turn which follows yours. The speed of this large form drops down to 30 feet per round. Once you’ve commanded it to change the form, you can take a bonus action to mount it. This makes you both invulnerable to melee attacks and unable to make them yourself unless the target creature is flying. You can move your bastion on your turn or its turn, but not both. Every Round this Large form regenerates 10 hit points, and may make 2 attacks per round instead of 1. It returns to its Iron Defender form after 5 rounds of combat and must be updated to an Iron Bastion again.

or

Iron Defiler	(From Iron Hound)
AC: 18	HP: 130	Speed: 65 feet (30 feet)
Str: 21 (+5)	Dex: 9 (-1)	Con: 20 (+5)
Int: 3 (-4)	Wis: 11 (-1)	Cha: 1 (-5)

  Immunities: poison damage, Psychic damage, disease,
  Resistance: Cold, Fire, Force, Radiant, and Necrotic damage.
  Vulnerability: Piercing and Lightning damage
  Bite Attack Melee Attack: +10 to Hit, Reach: 5 feet, One Target, Hit: 24 (4d8 + 4) piercing.
  Claw Attack Melee Attack: +10 to Hit, Reach: 5 feet, One Target, Hit: 19 (3d8+4) Slashing.
  (Large form only) Slam. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 18 (3d8+5) bludgeoning damage.
  (Large form only) Poison Breath. The Iron Defiler exhales poisonous gas in a 15 -foot cone. Each creature in that area must make a DC 19 Constitution saving throw, taking 45 (10d8) poison damage on a failed save, or half as much damage on a successful one.
Commands:

• Attack – Construct attacks a target creature of choice. It deals both a claw and bite attack with an advantage if it doesn’t have to move to the target. It does not have an advantage if the hound has to move to attack, but still multi-attacks.
• Scout – Construct scouts ahead of you up to their movement speed before returning. Upon returning, it projects an image of what it saw using 5 of your tinker points.
• Change Form – For 15 tinker points, the construct stands on its hind legs and increases in size to become a large creature. This Larger form has a lower Speed (30 feet), however it gains These benefits:
    Fire Absorption. Whenever the Iron Defiler is subjected to fire damage, it takes no damage and instead regains a number of hit points equal to the fire damage dealt.
    Immutable Form. The Iron Defiler is immune to any spell or effect that would alter its form.
    Magic Resistance. The Iron Defiler has advantage on saving throws against spells and other magical effects.
    Magic Weapons. The Iron Defiler‘s weapon attacks are magical.
    Multiattack: The Iron Defiler makes two melee attacks.
  
  It remains under your control but has its own turn which follows yours. It returns to its Iron Hound form after 4 rounds of combat and must be updated to an Iron Defiler again.