Homebrew
You are a Construct.
Your size is Medium or Small.
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 have resistance to poison damage and immunity to disease, and you have advantage on saving throws against being paralyzed or poisoner. You don’t need to eat, drink, or breathe.
Your body has built-in defensive layers, which can be enhanced with armor:
You have resistance to fire damage and immune to the heat metal spell and can heal the amount of damage that would be dealt only to yourself rather than take damage. At 3rd level you know how to cast the heat metal spell with this trait without requiring vocal, somatic, or material components. Once you cast heat metal with this trait, you can’t cast that spell with it again until you finish a short or long rest, you can also cast either of those spells using any spell slots you have of the appropriate level.
Intelligence, Wisdom, or Charisma is your spellcasting ability for these spells when you cast them with this trait (choose when you select this race).
You are proficient with firearms. As well you have a built in firearm that channels the fire within you rather that ammunition. This weapon has a short range of 30ft and long range of 90ft before imposing disadvantage, on a hit does 1d10 fire damage. You add your Dexterity modifier + proficiency bonus to this weapon. Your firearm folds into your hand allowing you to use both hands and in combat flips back into your firearm. When you are not in combat, you can use a bonus action to light a fire or make it light up for 10 feet of bright light and 15 feet of dim light.
As a bonus action, you can channel your flames into your construct feet. When you do so you have a hover speed of 5ft and ignore all difficult terrain and can move over liquid bodies like magma and water, as well your walking speed increases by 10ft. Your flames end after 10 minutes and can end it early if you choose, this trait can be used once and recharges after a short or long rest.
You have proficiency in perception and investigation skill checks. As a bonus action, you can choose one target to have tracked when you do so your integrated firearm ignores half and three quarter cover as well ignores disadvantage on short range attacks with your firearm. Once you use this trait you can’t use it again until you finish a short or long rest. At 3rd level, if you have a target tracked and escape from you can hold your tracking of that target for up to 1 mile once they leave that mile your tracking ends.