While this isn't an electronics question in itself, it is a problem faced by many of us when finishing off an electronics project in an attempt to create a professional finish.
It is most likely done by a screen-printing process. These are low-cost for one-off or low quantity production runs.
Figure 1. A screen-print jig. Source: Guitar Fool.
The linked article author sends his artwork out to have the screen created. He then fastens it into his jig, presses it down on the panel and squeegee's the ink through.
If you weren't trying to get an exact colour match I would recommend that you have the panel made. Many of the PCB manufacturers make front panels too as the processes are quite similar: silk screen (solder and component designations) and drilling and routing. They can generally offer aluminium and plastics.
Figure 2. Panel-Pool are one such company, in Europe, at least.
Panels can be "pooled" (assorted customers' jobs run through on one common panel before final cut-off) just as PCBs are. I used this company, oddly enough, for a mechanical part that had a fine grid of small (< 1 mm) holes. The task had been declined by the machine shops in my area. The laser cutting shops said they couldn't do it either due to the lead-in generated by the standard laser equipment. The PCB shops, on the other hand, do small holes all the time.