This is a simple Panel Plug Dummy for 12mm and 14mm holes when no real plug is to be installed. Other sizes may show up in future or just scale the ones available when needed. FreeCAD design files and output models are available at CeDeROM-STUFF.git [1][2] and MakerWorld [3][4].

[1] https://gitlab.com/cederom/cederom-stuff/-/tree/master/3D/models/electronics/panel_plug_dummy
[2] https://github.com/cederom/CeDeROM-STUFF/tree/master/3D/models/electronics/panel_plug_dummy
[3] https://makerworld.com/en/models/116839-cederom-panel-plug-dummy-12×20
[4] https://makerworld.com/en/models/116844-cederom-panel-plug-dummy-14×20