simple & short the person who carried it must have received the detainment challan, he shall present it at return journey and claim it for taking back. there will be no problems to carry it back.
reasonable people when carry any item to carry back declare it at customs with an application for temporary import release for period of journey.
The customs write up complete details of equipment with model serial & specs of the equipment in duplicate with date of issue & expiry, mentioning passport details of carrier. -
upon return the copy is presented with physical evidence of equipment and it is allowed for export,
cheers .. recite fateha for the quad copter with filming capabilities.