A light weight composite is fabricated by adding hollow glass microsphere (HGM) as a reinforcement material to the matrix which is unsaturated polyester resin. Different volume fractions of ( HGM) from (30%) to (70%) are used. (HGM) are chosen because of their smooth glass surfaces that enable them to be mixed uniformly through out the resin matrix. The study shows that the resultant composite has enough hardness value and can be molded in Templates and worked easily. The low density of the composite which is only (0.62 gm/cm3) with high compressive strength and low thermal conductivity coefficient make it suitable to be used as untraditional, low cost building material, in addition to repair surfaces and antiquities.