We designed a 3D printable nozzle with a static mixing section that would mix the materials just prior to extrusion. After several iterations of the design, we had a nozzle that could reliably mix the two components and extrude it into the gel. The final nozzle can be seen in the image on the right.
Hajash, K., Sparrman, B., Guberan, C., Laucks, J., & Tibbits, S. (2017). Large-Scale Rapid Liquid Printing. 3D Printing and Additive Manufacturing, 4(3), 123–132. https://doi.org/10.1089/3dp.2017.0037