A device comprised of hair-flow-channel guides continuously moved over the surface of the scalp. A track cap of parallel tracks is placed on the head to guide device's movement over the scalp along non-overlapping rows. At the front of the device is a hair-tensioning straightener that pulls hairs perpendicular to the scalp before and during processing. A bend-under assembly, formed by two pinching conveyer belts, facilitates hair exit from the channels by bending scalp-attached hairs beneath the walls of each hair channel. Intermittent intersection of each channel by an obstructing member isolates one or a few leading hairs for processing and forces trailing hairs to wait their turn for cosmetic processing behind it. Isolated scalp hairs may be cosmetically processed in ways including coloration; cross-section reshaping, hair-extension attachment and removal, and cutting to length according to position along track. Hair extensions removed at one position along a track cap are conveyed to corresponding holding clips and loaded in an order so as to permit their reattachment to the same scalp area. Hair extensions so held can be channeled and isolated for attachment, as are scalp hairs. A bend-under assembly can be used to draw one or a group of isolated hairs longitudinally through the chamber in which they are isolated facilitating cross-sectional reshaping of hairs or cutting to a preprogrammed length. Intersecting member and cosmetic processing actuation synchronized by computer.