In this paper we report the in-house synthesis of optical grade PMMA suitable for fiber development and fabrication of a large core micro-structured polymer optical fiber (mPOF). We have designed an mPOF with a core area of 580 μm2 and single mode performance at a wavelength of 650 nm. The photonic cladding is composed of 3 rings of air holes with a filling factor of 0.58 ensuring in practice a single mode performance at the design wavelength of 650 nm. The designed mPOF fiber was fabricated using the stack and draw technique, however some deformation of the structure of the photonic cladding has been observed during final stage of fiber drawing. The influence of this development imperfection on the overall fiber performance has been modeled. Finally the optical properties of the fabricated fiber were measured and a comparison between these and the modeled properties was made.