Dimensional synthesis refers to design of the dimensions of manipulators by optimising different kinds of performance indices. The motivation of this study is to perform dimensional synthesis for a wide set of spatial manipulators by optimising the manipulability of each manipulator around a pre-defined task point in the workspace and to finally give a prescription of manipulators along with their dimensions optimised for velocity and force transmission. A systematic method to formulate Jacobian matrix of a manipulator is presented. Optimisation of manipulability is performed for manipulation of the end-effector around a chosen task point for 96 1-DOF manipulators, 645 2-DOF manipulators, 8 3-DOF manipulators and 15 4-DOF manipulators taken from the result of enumeration of manipulators that is done in its companion paper devoted to enumeration of possible manipulators up to a number of links. Prescriptions for these sets of manipulators are presented along with their scaled condition numbers and their ordered indices. This gives the designer a prescription of manipulators with their optimised dimensions that reflects the performance of the end-effector around the given task point for velocity and force transmission.