Apparatus and associated methods relate to an array of individually readable distance sensors disposed along a first axis on a platform and configurable to detect penetration of a first plane containing the first axis, and an array of individually controllable light emitting indicators disposed on the platform along at least a second axis and configurable to emit visual indicia to a user out of the first plane. The visual indicia may, for example, be associated with the detected penetration. A reconfigurable predetermined detection window may, for example, be generated by associating adjacent sensors detecting input during a teaching operation. The detection window may, for example, be further generated by determining at least one distance threshold profile as a function of input received from the adjacent sensors during the teaching operation. Various embodiments may advantageously enable efficient configuration of generic sensing and indication units.