So I really was inspired by Xanathar's common magic items. So many cool things that players'd love (or think convenient) but not really something that'd heavily affect the game's balance. Then I had a load of ideas that *maybe affect the game's balance. Ok, some didn't, some were stupid, but the more stupid the idea, the more to discuss, right?

Expressive helmet (common)
This helmet (or mask) has a face on it (which may be demonic, angelic, monsterous, beastial) mimicks and exaggerates the expressions of the wearer beneath. (Ideal for a very scary samurai)

Helmet of total alignment (cursed)
You know that cursed helmet that gives you the opposite alignment? This one just makes your alignment more extreme

Death wagon (common)
This wagon has is propelled by the labour of animated skeletons built into the construction. Get really imaginative with how this could work, because I can't put that much metal into writing.

Perfect, infinite soap (common)
This is soap that cleans without deforming or decreasing. It doesn't irritate sensitive areas, and it's difficult to drop.

Tasteless perfume (common, cursed)
Upon applying this perfume, unless the user is immune to charm, the user makes a wisdom save, needing 20, should they pass, they know the stuff is rank smells rank, they have disadvantage on all charisma rolls for the next eight hours. Should they fail, they think it smells excellent, and the DM is encouraged to tell them they have advantage.

Amplifier (common)
This mysterious magical box has a wire that when attached... makes your instruments sound louder and more awesome.
Floating keyboard (common)
This floating instrument floats at waist height provided it carries no more than ten pounds.
Band in a bottle (rare, requires attunement by a bard)
As an action, one can release the band of 1d6 members, who appear as translucent Djinn. They always carry instruments that compliment the choice of the bard. The bard gets advantage on all performance rolls, musical attack rolls, and enemies get disadvantage on saving throws for one minute. This item can only be used once per long rest, and a d6 is rolled. On a 6, the band played their last performance.

Expression wands:
Wand of Screams (common)
Wand of Manic laughter (common)
Wand of Sobs (common)

dentures of doom.
(more likely to be more like a gumshield or set of fake fangs than replacement teeth)
You gain a bite attack, which you are proficient in.
Common- D4p
Uncommon D6, can be used as a bonus action.
Rare- A d6 with an extra ability. An extra d6 of fire damage for example.

Dread Flail (common)
The ball'n chain is more of a ball'n talking head, as a free action, you can use the head to talk, have the head cry or wail or laugh, choose it's expression, and so on. The Head could be that of a freshly severed humanoid still dripping blood, a skull, a sculpture or metal construction.

Hat of a hundred eyes (requires atunement)
You wear the animated stalks of the smaller beholder offshots on your head
Uncommon- Visible folks have disadvantage sneaking up on you.
Rare/very rare/legendary- you have access to your dm's choice of eye rays of varying power (As beholders are big creatures, we're talking observer/spectator levels at best), which are chosen randomly. Each use is an attack action.

Ghost limb (common) Requires atunement
When this iron torc is fastened to a limb with an amputation or deformity, as an action can form a ghostly limb (matching the shape of what should be there) this takes concentration.

(flesh) Replacement... (varies) (took some inspiration from the goblins comic, and I think these need a lot more "fleshing" out than I've given them)
Spoiler
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..Of the tree- When the seeds are planted in the wound, the blood feeds life; The missing flesh is replaced with a tree-like flesh that fills cavities and grows into missing limbs.
Common- (Yew,Oak,Birch,Gum etc)- Replaces the limb just fine. Gives an unarmed strike of 1d4.
Uncommon- Lightwood- Replaced Flesh weighs half as much, you can carry a little more.
Rare- Ironwood- +2 to AC when unarmoured.
[b]..Of the earth[b]
Common- Clay/stone/sandstone/limestone/marble; Once you've filled the wound with the enchanted substance, which is often only a handful, the appropriate ground material will add to the replacement's mass and it will form what was lost. This must also be done to repair damage. The insides of earth-flesh will be porous to reduce weight.
Uncommon- Crystal. It looks very nice, and can be an arcane focus.
Rare- Volcanic= You can cast burning hands three times a day.
Legendary- Diamond. Can cast chromatic orb as a cantrip.
[Mechanical]
Common- Steel. It's a metal arm/leg. Cool right? counts as half a shield (+1 ac) if you're not using a shield. Has weight. Repair is a pain.
Uncommon- Mithril- It's a lightweight metal arm. (+2 ac)
Uncommon- Oricalcum- It's an arcane-focus metal arm (+1)
Rare- Adamantine- It's an unbreakable metal arm. A +2 shield (+3 ac)
Very Rare- Azer- It's so perfect it looks like flesh, you can have it heat up and do a d10 fire damage to enemies who touch it, or add a d6 of fire to your melee weapon. (+2 ac)


Gloves of shameful submission (cursed)
Like the spider climb gloves... only if you're knocked prone, you'll stick yourself prone.

Orichalcum (common)
This rare, beautiful and valuable metal is conductive to all energies and thus function as an arcane focus and can be crafted into any suitable shape (a weapon, jewelry, a holy symbol) The material is otherwise unremarkable and offers no bonuses.

Gear of the insane scuba (very rare, attunement)
You gain a swim speed equal to your move speed.
You gain immunity to fire damage and heat effects. You gain vulnerability to cold.
You gain the ability to see through lava as if it were water.

The Magicklock series. (common)
It's a weapon, a wand or staff, shaped like an early firearm, often very ornate or eccentric. You use Dex to hit, Dex is the save, and add dex to the damage. Crossbow proficiency applies to relevant Magicklocks.
Heavy Magicklock: Firebolt, Ray of frost, Eldritch blast, chill touch (Either as a ray, or you fire the hand from the weapon). Re-skin elements as appropriate.
Light Magicklock: Lower the dice by one.
Hand Magicklock: Lower the dice by three. Anything that can't do that can't be a Hand Magicklock

Considered spells for rarer variants- Burning hands, Witchbolt, Ray of sickness, ice knife. Potentially, one could do 2d cantrips, but that'd need to be rare for balance given that it could be used as part as a multi attack.

Circlet of Impeccable hair (common)
While wearing this discrete circlet, the Hair will be clean and cannot be sullied, knots and dandruff cannot form, any attempt to style the hair will have advantage and recieve a +10 modifier, and the hair will maintain excellence in even pitched battles. The circlet also works on all facial hair, and is thus a favoured item of dwarvenkind.

Circlet of Incredible hair (common)
Though this circlet cannot cure baldness, anyone wearing this item has all head hair explode in a growth of 2 inches every minute, till it is both impressive and the wearer wishes it to grow no more (the hair will grow if it is not impressive, regardless of the whims of the wearer) The hair in it's excess weighs little and often rustles with power. As a bonus action, the wearer can have the hair move in any way they like (though it's not effective in combat)Barbarian rage causes temporary enlargement of incredible hair. The Thaumaturgy cantrip can cause Incredible hair to glow. Certain Circlets also colour the hair, and sentient circles of incredible hair can create sentient hair. The Circlet of Incredible hair usually works on facial hair; although beards are optional, eyebrows are mandatory.

Armour of Shame (cursed, common)
A normal Armour, perhaps masquerading as a magical set. When attuned, the armour, and all things worn underneath, become transparent as if made of glass, and the Armour's refractions shall endeavour to depict the body in the least flattering light. The wearer does not see this effect.

Lantern of trapped Patrons. (very rare, requires attunement by a non-warlock of a different patron)
Carrying this sentient lantern gives you a warlock features of a level equal to half your level +/- your charisma modifier. You do not get the hit points or ASI's, and the spells are chosen by the lantern. The Lantern must be carried in hand,it acts as a focus, it may adopt the form of the tomb/blade and will control the familiar. The patron may be enslaved and bound in it's form, or it could be a self imposed prison. Going against the patron may result in... As far as sentient items go, these can get pretty bad. Many outsiders may object to a trapped fiend,celestial or fey, and a saviour'll be owed big.

Codpiece of convenience. (common)
You'll never need to pee while you wear this item.

Skull gun. (common)
So you put a crossbow into a helmet. Then you shoot it as a bonus action, and take an action to reload it. It's so stupid that your players will love it. Do it for Gunther.