Here you have a 3d model of an L bracket + washer that I designed in SolidWorks. I have uploaded the .3mf file, as well as the .stl and .sldprt files. In the pictures you can see the real-life print, the dimensions, and a render. I designed these specifically to make a monitor stand, out of some wood scrap I had laying around. The SolidWorks part can be modified to the dimension you need. Happy printing!