The IP2I (Institute of Physics of the 2 Infinites) with the national platform LMA (Laboratory of Advanced Materials) currently produces the mirrors of all the current large interferometers of gravitational wave detectors (VIRGO, LIGO, KAGRA). The investments of the VELOCE project are requested to prepare for the major future projects of gravitational wave detectors planned for 2030. Being the only one in the world to be able to achieve the scientific performance required by these mirrors with a principle of surface treatment by thin films at the micron scale, the LMA is positioned to maintain its technical advance for the realization of future mirrors necessary for the realization of gravitational wave detectors of 3rd generation. The idea is to offer in Lyon a unique offer for the manufacture of ultra-efficient large-size mirrors, on the order of a metre, weighing several hundred kg and homogeneous to the micron with the growth of the sapphire substrate, mechanical and optical polishing and finally the surface treatment by thin films of which we are the unique specialists in the world. This development implies an extension of the existing building, the redevelopment of premises and the purchase of a set of equipment to build an international competitiveness machine that is the subject of this request.