  A persistent lamination for a knot K is an essential lamination in the
complement of the K, which remains essential after every non-trivial Dehn
surgery along K. In particular, this implies that all of the Dehn surgery
manifolds have universal cover R^3. This paper presents a method for building
tangles T with the property that every knot K obtained by tangle sum with T has
a persistent lamination. A natural generalization to 2n-string tangles is also
given.
