We are developing a method that permits ditopic molecules, in the form of linear templates, to position complementary molecules in the solid state for reaction. The templates operate by preorganizing reactants by way of hydrogen bonds for [2+2] photodimerization. In this talk, we will demonstrate how linear templates enable chemists to construct molecular targets. The targets include linear and bent molecules. Additionally, we will show how the products can be used as building blocks for the construction of porous metal-organic solids. The design principles discussed here may lead to the development of universal assemblers capable of fabricating a wide range of molecular products.