Each year I do a cell project with my middle school students during our unit on cells. Students, in groups, are charged with creating a 3D model of a cell. The twist is that the organelles can't be represented as they actually look, but must be represented as their function. For example, the mitochondrion might be represented as a power plant because the mitochondrion converts energy stored in food into ATP for cells.
You can get a copy of this project for free on TPT, TN, TES and Syllabuy.