Yes, it is possible to use 2x4 lumber for table legs. However, there are a few considerations when using 2x4s as they are typically used for construction purposes rather than furniture making. One major consideration is aesthetics; 2x4s have a more rough and utilitarian appearance compared to traditional table leg options such as turned hardwood or metal legs. Additionally, due to their larger size, 2x4s may not provide the most refined look and might be disproportionately heavy-looking compared to smaller tables. Despite these drawbacks, if rustic or industrial style fits your design concept or if you are working with limited resources or budget constraints, 2x4s can certainly be used effectively for table legs.