Got a few ideas:
1. Get a couple of piercings on your pussy lips each side (Shouldnt be done home alone but in a place for that...), And then once you got 3-5 each side, start wearing over knee socks and use rope on the socks and your pussy lips as straps/garter belts. This way you should be able to stretch them nicely over time.
2. Same as "1." but instead use pegs. Thats the home made version of it. Less permanent and probably not working as good.
3. You probably know some people with ear tunnels or have at least seen a few. Go for the same but for your pussy lips.
4. "1." and "2." could be done with your clit too I guess.
5. If its just plain destruction you are after, there are pins, needles, nails, cigarettes, razor blades... There is plenty more to cause permanent damage, if thats what you are after.
6. Tattoos are considered as permanent damage too by some, especially when you "write" something on there thats... not for your benefit in the long run.
I think I am done for now. If you end up wanting more of my input, feel free to ask for it. I am a visual guy. I bet many of the kink talk users would want you to upload pic of the aftermath of these tasks to your album, same as I do.
Happy suffering/destroying your cunt.
Edit: 7. Heavy duty duct tape can be quite some fun too, spreading your cunt with it for a while, again, more of a home made idea than some of the others.