Easy - Take the back out of a hoop earring of whatever colour you want it to be. I did this with a funky rainbow one and it worked fine. If you squeeze it a bit so it fits your lip best it should stay all day!
How To Make A Lip Ring Thats Real?
Get a pece of metal and bend it and put in your lip and close it with pliers into a hoop
What? Squeeze a post for an earring? No! Don't ever do that it will fall out or you will swallow the backing of the post.. Not fun.. Been there! Buy a captive ring or a horseshoe. Don't be cheep with your pearcing... You will pay for it in the end... Do it the right way with the right metal!
Just buy one. They're not too expensive.