sla apparatus from interfering with features in the parts a structural shield such as a dome may be place around the feature and then discarded at the conclusion of the sla process application_number US 62537107 A description a hearing instrument 10 comprising a shell 20 and a faceplate 30 is shown in the user 39 s ear canal 12 in fig1 the shell 20 has a shell tip 40 comprising a receiver hole 42 and an optional vent hole 44 the receiver hole 42 and the optional vent hole 44 are shown again in perspective views of the hearing instrument shell tip 40 in fig2 and 3 although the shell tip 40 is shown with a flat surface in fig2 and 3 and in the subsequent figures it may be rounded or assume some other shape an apparatus 100 for fabricating the hearing instrument shell 20 using stereo lithography sla is shown in schematic representation in fig4 with a portion of the shell tip 40 the figure also shows support structure elements 110 although these support structure elements 110 are illustrated as thin rectangular columns in the figure they may assume the shape determined by the particular sla process employed since the support structure elements 110 are designed to extend to a solid surface they will enter openings in the underside of the device being fabricated for example in fig4 they extend into the receiver hole 42 and the vent hole 44 after the part has been completed the portions of the support structure elements 110 remaining in the receiver hole 42 and the vent hole 44 must be removed further if the receiver hole 42 has a shape other than.