Tinker Familiar

You use your Tinker's Tools and Artificing experience to construct a body for a single clockwork companion and, with your knowledge of Arcana, summon a sentient spirit (your choice: celestial, fey, or fiend) to inhabit it and assist you until it is dismissed. This clockwork body can look like a common animal (i.e.: bat, cat, crab, frog (toad), hawk, lizard, octopus, owl, poisonous snake, fish (quipper), rat, raven, sea horse, spider, weasel, etc.) or be of your own imagination.

As an Action, you can temporarily dismiss your Tinker Familiar's animating spirit, causing it to depart, leaving behind the shell of its clockwork body, and wait in a pocket dimension for you to resummon it. As an Action while it is temporarily dismissed, you can re-summon it from this pocket dimension to inhabit a suitable clockwork body within touching-distance of you. You can also opt to construct and keep multiple clockwork bodies for your Tinker Familiar's animating spirit to alternate between. You may use an Action to switch your Tinker Familiar's animating spirit between two different clockwork bodies, but only if you are touching both bodies simultaneously. Otherwise, you must temporarily dismiss it with one Action and then re-summon it with another Action. 
Alternatively, you can dismiss your Tinker Familiar's animating animating spirit forever, leaving its former body behind as an inanimate construct, the parts of which are 75% as valuable as they were when they were originally used to build it. Or, if you so choose, you may dismiss your Tinker Familiar completely, severing your bond with its animating spirit while allowing it to remain attached to its clockwork body though it has departed from your service.

 You can't have more than one familiar at a time. Though you may additionally have multiple Replicas of your Tinker Familiar active using the Flock of Familiars spell, you can only ever have one true Tinker Familiar active at a time. If you attempt to make a new one, the original companion will break, resulting in scrap parts half the value of those originally used to build the clockwork body, and the spirit which gave it life will disappear deep into the Weave, from which it can only be re-summoned by recasting the [Tooltip Not Found] spell and succeeding both a DC:25 Charisma Check and a DC:25 Arcana Check. Additionally, casting the Find Familiar spell while you have a Tinker Familiar active will result in the spirit leaving the clockwork body of a Tinker Familiar and manifesting as an ordinary Familiar as produced by the Find Familiar spell.

 When the Tinker Familiar drops to 0 Hit Points, its animating spirit disappears, leaving behind the broken scrap of its clockwork body form. It returns after you repair its clockwork from and re-cast this spell again.

Your familiar acts independently of you, but it always obeys your commands. In Combat, it rolls its own Initiative and acts on its own turn. Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its Reaction to deliver the spell when you cast it. If the spell requires an Attack Roll, you use your Attack Modifier for the roll.

Your Tinker Familiar, regardless of it's size and of which kind of spirit it possesses (celestial, fey, or fiend), will have the following traits:
Magic Resistance. The Tinker Familiar has Advantage on Saving Throws against Spells and other magical effects.
Movement. 20ft. speed, 30 ft. Fly/Climb/Burrow/Swim (Only 1)
Communication. Knows the languages of it's creator but cannot speak. While your familiar is within 100 feet of you, you can communicate with it telepathically.
Blindsight. 120 ft. (Blind beyond this range)
Mind's Eye. If your Tinker Familiar is within 100 ft. of you, you may use an Action to see through your Tinker Familiar's eyes and hear what it hears for 1 minute or until the start of your next turn, gaining the benefits of any special senses that the it has, including its Blindsight. During this time, with regard to your own senses, you are considered Blinded and Deafened in your own body.

The Tinker Familiar has the following traits depending on it's size:
Tiny: 10 minutes to complete,  HP = 2d4 + Casting Mod., AC 13 (10 gp to build)
Small: 30 minutes to complete, HP = 3d6 + Casting Mod., AC 14 (50 gp to build)
Medium: 1 hour to complete, HP = 4d8 + Casting Mod., AC 15 (175 gp to build)
Large: 5 hours to complete, HP = 5d10 + Casting Mod., AC 16 (300 gp to build)

Actions:
Zap.  Ranged Weapon Attack. +4 to hit, one target. Hit: 6 (2d4 + 2) lightning damage.
(The die used gets doubled (4d4 + 4), tripled (6d4 + 6) and quadrupled (8d4 + 8) for each size above Tiny)
Hit. Melee Weapon Attack. +4 to hit, one target. Hit:  5 (1d6 + 2) bludgeoning, piercing OR slashing. (your choice)
(The die used gets doubled (2d6 + 4), tripled (3d6 + 6), and quadrupled (4d6 + 8) for each size above Tiny.)

 The Tinker Familiar has the following additional Actions available to them depending on the kind of spirit animating it:
Celestial: Healing Touch (3/Day). The Tinker Familiar touches another creature. The target magically regains (4d4 + 1) Hit Points and is freed from any curse, disease, poison, blindness, or deafness.
Fiend: Hypnotic Gaze (3/Day). The mechanical eyes of the Tinker Familiar sparkle with opalescent light as it targets one creature it can see within 30 feet of it. If the target can see the Tinker Familiar, the target must succeed on a DC 17 Wisdom Saving Throw against this magic or be Charmed until the end of the Tinker Familiar's next turn. The Charmed target is Stunned. If the target’s Saving Throw is Successful, the target is immune to this Tinker Familiar's hypnotic gaze for the next 24 hours.
Fey: Mechanical Panpipes (3/Day). From out of the Tinker Familiar, a mystical tune plays, sounding oddly like panpipes. Any creature within 60 feet of the Tinker Familiar that can hear the tune must succeed on a DC 13 Wisdom Saving Throw or be affected as described below. Other Tinker Familiars, fey creatures, and creatures that can’t be Charmed are unaffected, as are you and any allies you select up to 1+(your Spellcasting Modifier). An affected creature can repeat the Saving Throw at the end of each of its turns, ending the effect on itself on a Success. If a creature’s Saving Throw is Successful or the effect ends for it, the creature is immune to these Mechanical Panpipes for the next 24 hours.
            Choose one of the following magical effects: 
                      Charming Melody. The creature is Charmed by the Tinker Familiar for 1 minute. If you or any of your companions harms the creature, the effect on it ends immediately.
                      Frightening Strain. The creature is Frightened for 1 minute.
                      Gentle Lullaby. The creature falls asleep and is Unconscious for 1 minute. The effect ends if the creature takes damage or if someone uses an Action to shake them awake.