Skins

Skins are new skins for weapons doing the event updates. They can be won as prizes for completing the tiers. If you have the weapon, and you win a skin, you will just get the new skin and the original skin would still be there. If you don't have a weapon and win a skin, you will get the original weapon for free. Dual Rookie Machine Guns, Hunter Rifle, Automatic Shotgun, and Thumper were the only event weapon which its skin version was available for sale using real life currency.

Easter Egg Hunt

 * Blunderbuss - White and Golden Skin.
 * Revolver - Water Gun Skin.
 * Double Barrel Shotgun - The Line Skin.

Hand Grenade Fest

 * Howitzer Gun - Flaming Hot Skin

Road to Glory

 * Grenade Launcher - Red Hot Skin
 * Dual Grenade Pistols - Green and red checkerboard Skin.
 * Guitar Machine Gun - Tiger camo Skin.

Summer Camp

 * Missile Launcher - A golden graffiti painted skin with red missiles.
 * Scoped Assault Rifle - Blue, green and yellow Skin

Ghostbusters 30th

 * Plasma Punch - Grey and yellow striped Skin.
 * Zap Gun - Black and yellow striped Skin.

Ninja Path

 * Winter Ghost Rifle - Green camo Skin.
 * Anti Material Sniper - Red camo Skin.

Carnaval Update

 * Dual Rookie Machine Guns - Brazilian flag themed Skin.

Chinese New Year

 * Scoped Rocket Launcher - Chinese Skin
 * Dual Revolvers - Chinese Skin

Easter Egg Hunt 2.0

 * Hunter Rifle - Blue based colour, with a white sketch that seem like the Warrior Bunny's head.

Salute Our Troops

 * Automatic Shotgun - Silver-gold camo Skin

Summer Camp 2

 * Thumper - Smoking Aces Skin
 * Bazooka - Blue Shark Skin
 * Sniper Rifle - Colorful skin
 * Scoped Assault Rifle - Colorful Skin

Halloween Haunt

 * Double Barrel Shotgun - Monstrous Skin
 * Scoped Assault Rifle - Skeletal Skin

Winter Camp

 * Scoped Assault Rifle - Cadet Skin

Saint Patrick's Event

 * Guitar Machine Gun - Green leprechaun Skin
 * JP-BEK - Green-and-white Irish-themed Skin

April Fool's Event

 * Rookie Machine Gun - A cat Skin on the rookie machine gun

Mexican Fiesta 2

 * Blunderbuss
 * Brass and darker tone Skin
 * White handle and a golden "barrel" Skin

Fastest Gunslinger

 * Revolver - Water Gun Skin

Soccer Madness

 * Dual Machine Guns - Soccer Skin
 * Grenade Launcher - Red Hot skin.
 * Dual Grenade Pistols - Green and red checkerboard Skin.

Ghostbusters Event

 * Plasma Punch - Ghostbusters SkinPlasma Punch SkinCutted.png

Summer Camp 3

 * Revolver - Water Pistol Skin
 * Sniper Rifle - Colourful Skin
 * Heavy Machine Gun - Colourful Skin

Hand Grenade Fest 3

 * Siege Cannon - White and blue Skin
 * Dual Grenade Pistols - Flame Skin

Road to Glory 2016

 * Dual Pistols - Black Matador Skin
 * Airsoft SMG - Crimson Skin
 * Missile Launcher - Green Pixel Skin
 * Little Italy -Crimson Skin
 * Grenade Launcher - Red Hot skin
 * Double Barrel Shotgun - Aqua Skin
 * Stig Rifle - Aqua Skin
 * Revolver - Aqua Skin

Spooky Nights Event

 * Heavy Machine Gun - Crimson Skin
 * Double Barrel Shotgun - Monstrous Skin
 * Scoped Assault Rifle - Skeletal Skin
 * Armed Guitar Case - Halloween Skin
 * SMG Howling - Crimson Skin
 * Stake Launcher - Bone Skin

Soldiers Graduation Event

 * Bazooka - Blue Shark Skin
 * Howitzer Gun - Flaming Hot Skin
 * Anti Material Sniper - Crimson Skin
 * Guitar Machine Gun - Crimson Skin

Superstars Event

 * Sniper Rifle - Aqua Skin
 * Zap Gun - Aqua Skin
 * Plasma Punch - Ghostbusters Skin
 * Dual Grenade Pistols - Crimson Skin

Winter Camp 2016

 * Siege Cannon - Holiday Skin
 * Shotgun - Holiday Skin
 * Plasma Shotgun - Holiday Skin
 * Scoped Rocket Launcher - Holiday Skin

Chinese New Year 3

 * Dual Grenade Pistols - Chinese Skin
 * Howitzer Gun - Chinese Skin
 * Shotgun - Chinese Skin
 * Plasma Shotgun - Chinese Skin

Carnival 2017

 * Guitar Machine Gun - Neon Skin
 * Assault Rifle - Neon Skin
 * Shotgun - Neon Skin
 * Siege Cannon - Neon Skin
 * Rainbow's End - Neon Skin
 * Dual Revolvers - Neon Skin

Trivia

 * Currently, event weapon skins are usually obtained by using real currency while cash & gold priced weapons are obtained from events, with the exception of the green skin for the JP-BEK, which was released as an event prize at the same time.
 * The rarest skins in the game is the Easter Egg Hunt skins, but most likely the Double Barrel Shotgun skin due to the event's high difficulty of completing it and being the last weapon skin in the event.