How to make a opening door using CFrame Lua?

Here's an example of swinging a part on its right-side axis to open like a door. It first uses to the offset of the right side and then rotates it based on that CFrame, instead of the center.

It runs by simply putting the script in the part.

local increment = .05 -- best to keep it to a 5-base of 1(0)-base increment

function RunAnimation(p)
    local p = p or script.Parent
    local rightframe = p.CFrame + p.CFrame:vectorToWorldSpace( Vector3.new(1,0,0) * p.Size.X/2 )
    for i = 0, math.pi/2, .05 do
        wait()
        local newframe = rightframe * (CFrame.Angles(0, -i, 0) * CFrame.new(p.Size.X/-2,0,0))
        p.CFrame = newframe 
    end
end

RunAnimation()