  In the spectral analysis of few one dimensional quantum particles interacting
through delta potentials it is well known that one can recast the problem into
the spectral analysis of an integral operator (the skeleton) living on the
submanifold which supports the delta interactions. We shall present several
tools which allow direct insight into the spectral structure of this skeleton.
We shall illustrate the method on a model of a two dimensional quantum particle
interacting with two infinitely long straight wires which cross one another at
a certain angle : the quantum scissor.
