alright i know this has been up for a bit and i cant post the pictures on here because im at work and phone wont let me, but if ur looking for a good DIY fix that requires no welding here is what i have done and am continuing to do;
Use a drimmel and sand paper to cut and remove as much of the rust as you can, sand the surrounding area to make sure any surface rust under the paint is exposed, get some rustoleum rust reformer and coat the whole area.
Next what i did was a little unconventional. I took a few drywall patch kits and used the metal mesh backing part of them, depending on the size of your hole you may need a few peices, measure the general shape of the area you need to patch but go a little bigger because you need to put the peice inside the hole. next cut fiberglass matt or fiberglass cloth to lay over top the mesh backing peices, using a 2 part fiberglass resin mix up enough to cover the peice. have a peice of nylon string tied to the center of the piece, do this before mixing your fiberglass resin because the resin cures fast, apply the resin to the peice, make sure the peice is big enough to fit inside the hole but not so big that you cant get it into the hole lol. hold the string off the peice so that it does not stick to it.
after the peice has hardened and is ready to go inside the hole do so using the string to pull it flush against the inside of the hole.
now while holding it in place use the fiberglass resin again to fill the hole, and dont worry about using too much because you can always sand it down. after the hole is patched sand it down, i prefer to do it by hand but if you like using a sander then by all means. after it looks like a solid flush peice start the painting process.
all in all i did this and have been using this method the last few weeks on my car including making an entire new part of my hatch that had rusted all the way through. total cost in materials was as follows,
fiberglass resin and matt $25
paint to match my car $50
drywall repair kit, $10
i couldnt post pics of what i have done on here but they are on my other forum post here;
you can see the hatch and that whole bottom peice i cut off and redid with fiberglass, i have no body work experience and all in all while not perfect it looks a whole lot better then rust spots