In this paper, an inexpensive, easy–to–fabricate active magnetic mixer is presented. This mixer functions on top of a common magnetic stir plate and is capable of mixing two streams, each at flow rates up to 5 ml min–1. A liquid–phase photopolymerization technique is used to fabricate the device. An analysis of mixing efficiency is based on greyscale intensity measurements of two coloured streams passing through the mixer. A brief hypothesis of the mechanism of mixing is also presented.