  We introduce a novel and simple modulation technique to tailor optical beams
with a customized amount of orbital angular momentum (OAM). The technique is
based on the modulation of the angular spectrum of a seed beam, which allows us
to specify in an independent manner the value of OAM and the shape of the
resulting beam transverse intensity. We experimentally demonstrate our method
by arbitrarily shaping the radial and angular intensity distributions of Bessel
and Laguerre-Gauss beams, while their OAM value remains constant. Our
experimental results agree with the numerical and theoretical predictions.
