Help With Welds?

The problem is that you are passing too many arguments to the function weld. Instead, let's create a helper function that welds all the arguments together!

Here is my solution, with your code included:

local function weld(a, b)
    --Make a new Weld and Parent it to a.
    local weld = Instance.new("ManualWeld", a)
    weld.Part0 = a
    weld.Part1 = b
    --Get the CFrame of b relative to a.
    weld.C0 = b.CFrame:inverse() * a.CFrame
    --Return the reference to the weld so that you can change it later.
    return weld
end

local function weldBetween(...)
    local parts = {...} -- A list of all the arguments passed to this function
    local rootPart = parts[1] -- The first argument passed is going to be the part we weld everything to
    for a = 2, #parts do
        -- Weld all other parts to the first part
        weld(rootPart, parts[a])
    end
end

local welds = weldBetween(script.Parent.Handle, script.Parent.Part1, script.Parent.Part2, script.Parent.Part3, script.Parent.Part4, script.Parent.Part5, script.Parent.Part6)