6.—(1) Any person who intends to assemble, mix or otherwise manipulate any goods or to carry out such manufacture as is permitted under section 10(1) for entry into customs territory, where either the manufactured goods or the materials used in the manufacture thereof are dutiable, shall give the Director-General notice in writing of his intention and obtain his prior written permission to do so. Such permission shall be granted or withheld as the Director-General in his discretion shall think fit:
Provided that, if permission is granted, such manipulation or manufacture shall be carried out under customs supervision.
(2) Any manipulation or manufacture permitted under this section shall be subject to the regulations made under this Act and to such conditions as the Director-General may think fit to impose:
Provided that the Director-General may, in his discretion, give an allowance for recoverable and irrecoverable waste, but if recoverable waste is sent into customs territory, it shall be dutiable in its condition and quantity and at its weight at the time of entry.