I had both my nipples pierced just about ten years ago. I did have them done at a business (DermaTech, St Helens, Or) rather than any notion of DIY. And I didn't want to go through the 'discomfort' twice, so I went for broke and got them both done. It was excruciating but worth it.
When I left the salon, I had 16 guage hoops in. Since then, as the photos indicate, I've gone to progressively larger jewelry. As of about 3 years ago, I've outgrown anything available commercially, so I've had to make my own.
Right now, the pink inserts I'm using are about 5/16" across.
And I am VERY pleased with the results. I had no idea starting out that my nips would grow like they have but the results speak for themselves. I have pumped them in years past, and still do occassionally just for fun but the bulk of what you see is growth of the nipple accommodating progressively bigger objects.
Actually, on a certain level, I have come to think of the insert as an armature that my body builds flesh around.
I have had misadventures along the way.... the piercing will stretch at first, accepting a larger size it's not really ready for. Within 12 hours, I'll realize they aren't ready for that big a jump. Leave the oversize in there too long, and they get sort of seized in there. Then it's a REAL problem to get them out without tearing tissue inside the nipple.
They are 'out there', showing up no matter what shirt I wear. I am a CD and even with a bra on, they generally push through.
I work commercial construction (wearing just a tee shirt 99% of the time) and it's become common knowledge that they are pierced. "They have to be" is what one foreman said. No one on the job has ever seen them, but the evidence speaks for itself.