Specialized wooden container

NASA Johnson Space Center intends to modify contract 80JSC025PA006 for the purpose of adding a requirement for the awarded contractor, Optical Coating Labratories, to build a replacement shipping container so that the required MCAT telescope mirror can be shipped properly and safely to its destination on Ascencion Island.  Given that the current vendor has posession of the mirror, it is keenly aware of the delicate and critical state the mirror is in and can design a mirror that will safely protect the mirror while it is in transport and therefore guarantee the work the vendor has performed on the optical recoating of the mirror surface. Therefore, OCL is the only responsible source available to design and manufacture the required shipping container that will be specific to this mirror.  The Government intends to award this modification under the authority of FAR 13.501 since the value of the modification is less than the simplified acquisition threshold.  A separate procurement is not in the best interest of the Government due to cost and schedule constraints. Questions and/or comments are welcome.