Rack mount kit for under the desk for 1 unit devices. The additional brackets can be used for heavier devices. With these angles I fixed my 19 inch office switch under the desk.

I use M6 screws for the 10"/19" slot and 3x35 universal screws to fix the device under the table top.

Print settings for the example in the pictures: 0.4mm nozzle, 0.2mm layer, 15% infill, no supports.