This versatile construct stands between 3 ft and 5ft tall.To make this steel companion it requires 7 parts:

Control bracer:

this is the command bracer for the user of the Mechadroid. whilst in possession of this bracer you can give commands to the Mechadroid at any distance within 1000 feet. see through the constructs eyes, locate the droid or keep track of it's damage and repairs. Certain Artificers were able to combine this with arcane focus to provide spell assistance to the Mechadroid

Droidcore:

A droid core contains the recorded information and woven personality of the mechadroid. in an effort to even Gleam the constructed brilliance of an Eidolon these cores are able to slightly augment some of the capabilities of the Mechadroid, contain some low level spells, or create complimentary assistance to the owner. 

BODY PARTS:

Arms (each singular):

the arms are modifiable and able to be switched out to make Mechadroids the most versatile construct companion. the arms can house specialty tools, weapons or utility items to deploy at whim. it also makes them capable of switching skills depending on the arms attached. 

Mobility drive:

the "legs" of the Mechadroid. the mobility drive determines the maneuverability of the Mechadroid. the legs may also provide buffs or bonuses to the Endoplast underneath making them essential for day to day operation.

Endoplast:

the "skeleton" of the Mechadroid. Any parts from other mechadroids or constructs of an equal size that are overlayed ontop of this frame can be integrated into construct and used within minutes. This specialized skeleton contains the secrets of Clever's Arkwelder technology, some integration of phrax and spells to interlock any sectioned off part that could be prepared or scavenged. This Endoplast also gives the Mechabdroid it's starting feature and a slow autorepair function.

Cranium:

the Head and torso of the Mechadroids, this part focuses on the sensory devices, memory storage and overall look of the Mechadroid. Excessive damage to this part can render the Mechadroid inoperable. 

Based off of the 5e artificer steel defender the base stat block is the same for all of them and treated as the Endoplast. then when you add in the different parts of the Mechadroid you get to add on additional modifications to the stat block based off of what parts you change

BODY PARTS:

Endoplast:

you start from here. the Statblock starts off with a similar state setup as the steel defender. the core stats are 14, 12, 14, 4, 10, 6. the difference is that you CHOOSE which stats they get sent into. This cannot change after setup.  the Mechadroid has the following setup:

• AC= 15
  
• HP= 2+ highest mental stat +5 times character level (with a number of D8s equal to character level)
• Speed= 30 ft
• Damage immunity poison
• Condition immunities: charmed, Exhaustion, Poisoned
• Language: languages you speak
• Trait: Vigilant: the Mechadroid can't be surprised
• Trait: Might of the Master (minus the repair action since that is not immediately given)
  
• Trait: Low Powered Recovery: When outside of combat, the Mechadroid regains 1 hp per minute as long as their hp has not gone down to 0
• Trait: Steel Defender
  

Cranium:

• 1 Senses (barring true sight unless the part is specially crafted)
  
• 2 skills
• 2 saving throw proficiencies
• 1 stat increase or 1 action/bonus action
  

Arms (each singular):

the arms are modifiable and able to be switched out to make Mechadroids the most versatile construct companion. each arm can hold:

• 1 action/bonus action/reaction
• 1 stat increase
• 1 tool or skill proficiency (or expertise in a skill given by another part)
• multi attack if the 2 arms deal the same damage type / blank
  

Mobility Drive:

the "legs" of the Mechadroid. the legs provide:

• 1 reaction
• 1 stat increase
• 1 movement option
  
• 1 additional movement/ blank

Droidcore:

the heart of the Mechadroid. the droidcore provides:

• 1 trait
• 1 stat increase
• 1 Combo maneuver
  
• 1 additional trait/ save proficiency/ blank

Whilst the Mechadroids sport versatility  there are some benefits with sticking with an aesthetic and also some benefits for loyalty to a core.

Set Bonus

Whilst keeping to an aesthetic in which every part of the mobility drive arms and cranium match, the Mechadroid can unlock a new passive ability. This passive doubles up on what the Mechadroid's core aesthetic is whether or not it's new addition to combat ability, support ability, or mobility. The Mechadroid will have access to this feature for as long as it for external parts are the same or are aligned. 

Combo Maneuvers

When choosing a combo maneuver, the Mechadroid uses its entire action to set up a support action for your character. Each combo maneuver will have different activation triggers requiring your character to either be close by them in proximity or to direct or use an action towards them. This further magnifies the effect's outcome.

One example combo maneuver Lotus Healing.

• Action.
• The Mechadroid stays in one place, readying its dispersal arms to project any sortof healing done to it to a number of creatures equal to your proficiency bonus in a radius.
• Activation - casting a healing spell or effect to regain HP while within 5ft of the Mechadroid. 

Droid Core Special

There are special docents or 'cores' around Unknown that on their own give special attack actions or features by itself so long as the Mechadroid itself fulfills whatever condition the Docent will require. These special features can only be activated usually by the continued use or activity. 

Example. Kabuto Barrage. 

• Successfully deal damage a number of rounds equal to proficiency bonus. On the next turn, you may replace one of your attack actions with the following action. 
• Kabuto Barrage - Choose a point within 60ft. That point and every point in a 10ft radius is struck by a hail of explosive ammunition. Each creature in that area makes a DC (???) saving throw or takes 3x the amount of weapon attack damage die.