Do you already have a design/ setup in mind for what the PDF should look like?
Depending on how complicated it is, it'll be quite easy to make, or very difficult.
Here's a quick example of making a PDF (copied from the [url=http://www.fpdf.org/]FPDF site
, I added some comments to show what's going on):
// create a new PDF
$pdf = new FPDF();
// add an empty page
// set the font to arial, 16pts and make it bold
// create a cell 40 points wide, 10 high, and write Hello World into it
// output the pdf to the browser
The manual on that site is pretty decent, it explains most of the possibilities quite well.
Just a quick warning, it might take a while to get used to creating PDFs like this.
Try it out, see how far you get and let us know if you get stuck