Many of the enclosures I’ve used for my builds have plain brushed or anodized aluminium fronts. With these, all customization, drilling, labelling etc. is left to the builder. I’m actually quite fond of this plain, minimal look but occasionally some lettering would be helpful. This applies to the rear as well, I’m thinking RCA jacks that serve as inputs and outputs, multiple jacks for preamp inputs and so on.
There are of course professional solutions to this, with many builders specifying their graphic options at the point of purchase – HiFi2000 offer engraving and printing for enclosures bought from them. In the US Front Panel Express, and for Europe Schaeffer, offer a service whereby you use their software to design a panel which they use to custom design and manufacture a panel. Whilst the results are superb, when I looked into it, I found the price too high. For a one-off build, I suppose I might use one of these services, but I think I would rather put the money into another hardware build.
Years ago I used to build scale motorcycle models from Tamiya and it got me thinking about decals. After some searching I came across a company called Decc which manufacture vinyl lettering in a range of sizes and I bought a couple of packs to try them out. You can see the result of my first attempt in the image at the top of this post. They are certainly fiddly and time-consuming to apply, you need a good eye and a steady hand (neither of which I possess, but alas) but it’s a cheap option to consider.