A group of scientists at the Iowa State University were seeking to find a frugal alternative that would allow
them to hold soil substitutes for germinating and growing plants. They wanted something that was modular, scalable, and capable of housing simultaneous experiments.
They found what they were looking for with LEGO blocks, which despite being a toy, are made of high quality plastic, held to very precise standards. And, of course, you can build things with them! Which they did! Their results are reported in the PLoS ONE paper entitled : LEGO Bricks as Building Blocks for Centimeter-Scale Biological Environments: The Case of Plants.
Some information for this post obtained from the Science Direct article: LEGO bricks turned into scientific tool to study plant growth