The way most people learn to build and install channel letters is by working at a shop that does this work. There are not any schools for it that I know of. I guess you can call it an 'apprenticeship,' working alongside someone, but most real apprentice programs are a thing of the past. Along with other benefits once typically provided by union membership, apprentice programs are dying along with the unions.
People still speak of apprenticeships in sign shops, but these are usually not the type of training programs that existed in the past. To apprentice as an electrician these days still carries meaning. You will learn a lot, including theory. But an apprenticeship in a sign shop today often simply means you are working alongside someone who claims to be an expert and they are showing you how they personally do the job. But maybe they really aren't an expert, and you end up being trained by someone who may not be completely familiar with industry standards or code requirements. You may learn enough to install channel letters after a fashion, but not necessarily using best practices. The law is neither stringent nor consistent everywhere in the US for sign work. In many areas, a licensed electrician is NOT required for either manufacturing or installation. Standards for workers vary wildly. For example, many sign shop employees that service electric signs may know little more than how to replace lamps and ballasts. Troubleshooting is often not learned or practiced. If an underlying problem exists, they cannot figure it out.
The result is that today we have in the sign industry a hodge-podge of abilities and levels of expertise in connection with electric signs. In some cases, calling a shop for channel letters is like rolling dice. You may, for instance, get a sign maker that can make and install a lighted sign that will function for many years or one that makes signs that tend to last only a couple years. Or one that makes signs that have constant problems. I knew a shop that told clients that neon signs typically last only about two years, urging the clients to always buy only LED-powered signs instead. Why did they say that? Because THEIR neon signs typically lasted no longer than two years. They did not fabricate the letters themselves, nor the tubing. So either they were buying poorly made letters or using faulty installation practices. Either way, they assumed that two years was a normal life for neon tubing. So they were in the habit of telling clients that LED lamps last longer than neon. This is misinformation. I have seen neon signs burn for dozens of years. And what is the best-projected life for LEDs? Ten years, at most?
I am not taking sides in the neon versus LED debate here.
My point is that working at a shop that builds and installs channel letters may not always give you expertise in this area. Hopefully it will.
It may be the only thing you can do.
Brad in Kansas City