Most warforged take comfort in order and discipline, tending toward law and neutrality. But some have absorbed the morality, or lack thereof, of the beings with which they served.

Your size is Medium. To set your height and weight randomly, start with rolling a size modifier:

Size modifier = 8d6

Height = 3 feet + your size modifier in inches

Weight in pounds = 270 + (4 × your size modifier)

Your base walking speed is 30 feet.

As an action, you can transform into something, when you gain this ability you can only transform into one alternative form. You can reset your alternate mode to something else over a long rest.

The form can be a myriad of things, pick one of the following options.

Alternate Mode: 

you assume the stat block of a creature or vehicle you've seen before, that's no bigger than one size category larger than you at the time you use this ability. You maintain your personality but your character sheet is replaced with the creature's stat block. If you choose a vehicle, you maintain your previous stats, but can't make actions that the vehicle form prevents, such as grappling if the mode has no hands. 

To determine what you can transform into, take a creature's CR and divide it by 4, and round up the result, if the number is higher than your character level you can't transform into it.

(Ex: if you're level one, and saw a CR 5 creature and wanted to turn into it, you'd divide the CR by four and round up. In this case their level is 1.25 rounded up to 2, thus you can't transform into it.)

Master mode:

You transform into something that relates to one of your proficiencies, such as artisan's tools, smithy's tools, shields and more. While in this form you can no longer take actions of any kind, but you can be equipmented or used by others, and when you're used for the proficiency you choose, the user gains your proficiency bonus towards that relevant task and advantage. 

(Ex: you transform into a great sword, and you have a plus 3 proficiency bonus when using a greatsword, then whoever uses you, gains that bonus, on top of whatever bonus they already had.)

For others to determine your true nature in whatever form you're in, they must make an investigation check, with a DC of 10 plus your charisma modifier plus other relevant bonuses. 

You are metal given soul, form serving more than just function, something that's more than meets the eye, you gain the following benefits:

You have advantage on saving throws against being poisoned, and you have resistance to poison damage.

You don’t need to eat, drink, or breathe.

You are immune to disease.

You don’t need to sleep, and magic can’t put you to sleep.

When you take a long rest, you must spend at least six hours in an inactive, motionless state, rather than sleeping. In this state, you appear inert, but it doesn’t render you unconscious, and you can see and hear as normal.

You can speak, read, and write Common and one other language of your choice.

Your Constitution score increases by 1, and one other ability score of your choice increases by 1.

Transformers are an interesting race in the aspect of age, with most fully formed bots around the same age as humans. However, within the right circumstances, and with proper care, transformers have been reported to live for millions of years. You are immune to magical aging effects.