Your constitution score increase by 2 and one other ability score of your choice increases by 1.

You have a walking speed of 25ft. Slower than the average race as your robotic clockwork form takes more time and effort to move. 

Clockwork men can live indefinitely so long as they are consistently maintained. Unfortunately much of the knowledge of how to restore these magical constructs was lost along with the lost mine of the Phandelver's Pact. Without maintenance it is expected that clockwork men can only survive for about 15-20 years.

Clockwork men can have any alignment depending on who they serve/who created them.

Your size can be anywhere from 3ft to 8ft. Your size is medium or small. Some clockwork men are modelled after members of specific races, most commonly gnomes, dwarves and humans although some exist resembling elves and halflings and rarer races. No clockwork men were made to resemble orcs because of the deep-seated hatred of orcs by the Phandelver's Pact.

Armour plating is built in to your form. Your AC is equal to 13 + your proficiency bonus but you can not wear armour over the top of your plating. You can wear a shield and still gain this benefit.
You have disadvantage on stealth checks as your armour clunks and your gears whir.

You were created to have remarkable fortitude, represented by the following benefits:

You have resistance to poison damage and advantage on saving throws against the poisoned condition.
You don't need to eat, drink or breath.
You are immune to disease.
You don't need to sleep and magic can't put you to sleep.

You were created to specialise in one area. you gain proficiency in one set of tools and one skill of your choice.
In addition, whenever you fail an ability check attack roll or saving throw you can add 1d4 to the total possibly turning it into a success.
You can use this feature a number of times equal to your proficiency bonus and it resets on a long rest.

You gain access to customisable arm attachments to help you with tasks and in combat:

You have a crossbow that attaches onto your arm. You count as proficient with this crossbow while it's attached to you and it has the ammunition, loading and range (100/400) properties when you take the attack action you can make a ranged attack with the crossbow dealing 1d10 + your dexterity modifier on a hit.

You have a blade that attaches onto your arm. You count as proficient with the blade while it's attached to you and the blade has the finesse and light finesse properties. When you take the attack action you can make a melee attack with the blade against an a creature within 5ft of you dealing 1d6 + your strength/dexterity modifier (whichever was used to make the attack roll)

You have a shield that attaches onto your arm. While wielding this shield you gain a +2 to your AC. You can still only gain the benefits from one shield at a time.

You can incorporate tools with which you have proficiency into your arm.

By default you have a hand with fingers and thumb for fine motor control and holding other objects.

You can change the item attached to your arm as a bonus action on your turn. The item attached to you cannot be removed without your will while you are not incapacitated, unconscious or dead.

You can speak read and write common and one other language of your choice, typically one that your creator spoke.