This is an end cap that can be press fit on the end of a standard 2x4 stud. I'm using them as feet to level out my workbench.
I've included the Fusion360 design file in case you need to tweak the design or increase the height.
2x4_Cap_v3.stl | 12.0KB | |
2_x_4_Cap_v3.f3d | 100.5KB |