The present invention relates to a vascular prosthesis containing an active substance that has the capacity to stimulate the ingrowth of vascular cells, into the prosthesis. Also provided is a mold having a first mold half and a second mold half, the halves being movable relative to each other. A controller is electrically coupled to the forward-looking sensor. The relative proportion of standard verses sample ablated can be changed by altering the trajectory of the laser beam.