In this work, we build and test three memristor-based true random number generator (TRNG) circuits: two previously presented in the literature (Jiang, H.; Belkin, D.; Savel’ev, S. E.; Lin, S.; Wang, Z.; Li, Y.; Joshi, S.; Midya, R.; Li, C.; Rao, M.; Barnell, M.; Wu, Q.; Yang, J. J.; Xia, Q.: A novel true random number generator based on a stochastic diffusive memristor. Nature Communications 2017, 8:882; Rai, V. K.; Tripath, S.; Mathew, J. Memristor based random number generator: architectures and evaluation. 6th International Conference on Smart Computing and Communications, 2017, 125, 577-583.) and one which is our own design. The functionality of each circuit is assessed using the National Institute of Standards and Technology (NIST) Statistical Test Suite (STS). The TRNG circuits were built using commercially available off-the-shelf parts, including the memristor. The results of this work confirm the usefulness of memristors for successful implementation of TRNG circuits, as well as the ease with which a TRNG can be built using simple circuit designs and off-the-shelf breadboard circuit components.