Conventional semiconductor diodes dissipate energy in the form of heat when current passes through them. This is unwanted in, for example, cryogenic environments. Using a superconducting diode could mitigate this problem. These have been made by using special materials or combining multiple different circuit elements. We provide a systematic method of designing a tunable superconducting diode using a circuit of solely Josephson tunnel junctions. We show that even for a small number of Josephson junctions a strong diode effect can be achieved and that this method is stable under manufacturing tolerances. This method involves solving computationally inexpensive linear least squares problems to tune the Josephson energies of the junctions used.