GetBoundingBox.lua

local function GetBoundingBox(model, orientation)
	if typeof(model) == "Instance" then
		model = model:GetDescendants()
	end
	if not orientation then
		orientation = CFrame.new()
	end
	local inf = math.huge

	local minx, miny, minz = inf, inf, inf
	local maxx, maxy, maxz = -inf, -inf, -inf

	for _, obj in ipairs(model) do
		if obj:IsA("BasePart") then
			local cf = obj.CFrame
			cf = orientation:ToObjectSpace(cf)
			local size = obj.Size
			local sx, sy, sz = size.X, size.Y, size.Z

			local x, y, z, R00, R01, R02, R10, R11, R12, R20, R21, R22 = cf:GetComponents()

			local wsx = 0.5 * (math.abs(R00) * sx + math.abs(R01) * sy + math.abs(R02) * sz)
			local wsy = 0.5 * (math.abs(R10) * sx + math.abs(R11) * sy + math.abs(R12) * sz)
			local wsz = 0.5 * (math.abs(R20) * sx + math.abs(R21) * sy + math.abs(R22) * sz)

			if minx > x - wsx then
				minx = x - wsx
			end
			if miny > y - wsy then
				miny = y - wsy
			end
			if minz > z - wsz then
				minz = z - wsz
			end

			if maxx < x + wsx then
				maxx = x + wsx
			end
			if maxy < y + wsy then
				maxy = y + wsy
			end
			if maxz < z + wsz then
				maxz = z + wsz
			end
		end
	end

	local omin, omax = Vector3.new(minx, miny, minz), Vector3.new(maxx, maxy, maxz)
	local omiddle = (omax+omin)/2
	local wCf = orientation - orientation.Position + orientation:PointToWorldSpace(omiddle)
	local size = (omax-omin)
	return wCf, size
end