weapon_cubemap

This entity is not in the FGD by default.
See below for instructions on making it available.

weapon_cubemap in Half-Life 2.

Class hierarchy
CWeaponCubemap ↳CBaseCombatWeapon ↳CBaseAnimating ↳CBaseEntity
weapon_cubemap.cpp

weapon_cubemap is an entity available in Half-Life 2 series, Portal series, and Portal 2: Community Edition.

This entity gives the player a set of spheres models/shadertest/envballs.mdl, each with different reflective surfaces. It is used for checking cubemaps.

The commands to get it (typed into the console) are either impulse 81 or give weapon_cubemap. These commands are considered cheats, meaning that sv_cheats must be enabled for them to work.
You can switch to this weapon (after having received it) by typing use weapon_cubemap.

Tip:To equip and draw the weapon for quick work, developers can bind this command to a specific key. For instance, typing bind "X" "impulse 81"; "use weapon_cubemap" will bind it to the X key. (You may need to press it twice the first time you use it in a map.)

Note: does have it in a working condition but needs the model from another game

Workarounds

If your game does not have weapon_cubemap, rifle scopes could be used, such as the hunting rifle in Left 4 Dead 2, the AWP in CS:GO or the crossbow in Black Mesa, as alternatives.
Community mods have been made to implement it into games that do not support it natively:

• Team Fortress 2: Create a VScript file named weapon_cubemap.nut inside tf/scripts/vscripts/, paste in the following code and then type script_execute weapon_cubemap and switch to melee.

local cubemap = "models/shadertest/envballs.mdl"
PrecacheModel(cubemap)
for (local i = 0; i < 8; i++)
{
    local weapon = NetProps.GetPropEntityArray(player, "m_hMyWeapons", i)
    if (weapon && weapon.GetSlot() == 2)
		weapon.SetCustomViewModel(cubemap)
}

• Counter-Strike: Global Offensive: Tutorial by TopHattWaffle and Zool Smith
• Left 4 Dead 2: Tutorial by MrFunreal
• Weapon_Cubemap (Dev Tool): A simple replacement for the assassin glock by Jofoyo

FGD Code

@PointClass base(Weapon,Targetname, Parentname) studio("models/shadertest/envballs.mdl") = weapon_cubemap : "Cubemap preview spheres"[]