I found a model that is supposed to make sure my tool doesn't fall out of the players hand. It works with parts only, and I have unions in my tool so I've tweaked it a little but it isn't working, here is the script:

function Weld(x,y)
	local W = Instance.new("Weld")
	W.Part0 = x
	W.Part1 = y
	local CJ = CFrame.new(x.Position)
	local C0 = x.CFrame:inverse()*CJ
	local C1 = y.CFrame:inverse()*CJ
	W.C0 = C0
	W.C1 = C1
	W.Parent = x
end

function Get(A)
	if A:IsA("BasePart") or A:IsA("UnionOperation") then
		Weld(script.Parent.Handle, A)
		A.Anchored = false
	else
		local C = A:GetChildren()
		for i=1, #C do
		Get(C[i])
		end
	end
end

Get(script.Parent)
Anonymous