If you heve then get a 4 inch piece of old broom handle and drill a hole through it at one end and tie a bit of cord through it.
Next, use some thinners and clean a clean spot in the middle of the dent.
Heat up glue gun and put a huge dollop of glue on the end of the stick that does not have the cord on and push gently onto the dent and hold until glue set hard. This will take a few minutes.
Pull the string hard.
Heat a knife blade or something up and use it to cut through the glue.
The same tecnique can be used to pull small dents from body panels but you dont need the glue gun, just some glue gun sticks and a hair-drier. Don't strip the paint, heat up the dent with the hair-drier, melt glue stick onto hot panel, affix stick and let cool. Pull. Then re-heat the panel to remove the glue.