I don’t recommend this one for OP’s specific case. The method written here only teaches you how to weld things to characters via the attachment setup, but it doesn’t contain any information on how to script an actual pseudotool. I think that thread and OP’s case are different. In addition, OP won’t be able to animate the tool without using Motor6Ds and will have to manually weld the tool to the arm.
(PS: Code piece for doing the above is here, instance type will need to be changed to Motor6D)