Custom is defined under the forum name, thusly, "What are you working on? Bobbing a fender? Machining a new set of triple trees? Squirting custom paint? Hacking up a GFG? Carving some leather? Show us what you're doing." Rather than a strict definition, I tried to give examples. They all involve cutting, fabricating or refinishing (paint/powder-coating).
A lot of accessories require extra steps to install on these bikes, but they're still accessories. Now, let's say you were modifying the petcock, maybe painting it or changing it's outer appearance, I could consider that custom work. But the Pingle is an accessory, and while it does require special steps to install beyond the offical instructions, cutting, fabricating, welding, etc., are not part of it.
Another example is an aftermarket speedometer, say, from Drag Specialties. In and of itself it is an accessory, but if you cut up your gas tank to create a special recessed mounting location for it, viola, it becomes custom (or more accurately, part of a custom installation).
I'm not coming down on you, just trying to clarify.
