The 310mm*128mm*33mm brass case cost less than $500. It was used as a display model. There were six stems on the inside, of which the aperture was 3.4mm. So we could not cut M2 threads into the standoffs, and as the client rejected the M4 thread, so we just left them as holes.
Solution
Step 1: Check the file sent from the client, and give the quote and estimate arrival time.
Step 2: Programme and set the CNC miller, place the brass onto the plate, and the machine will process it automatically.