I used that printed-out one myself for some time, but in the long run I just wasn't satisfied with it. Like you, I didn't fancy hand-painting a five-pointed star either. So I printed out two plain stars that I found on the net (one for each side), but used a sticker sheet instead of regular printer paper. Then you can simply cut out and stick the stars on your chosen flag (this one is made from metal foil) and you have something nice and solid to paint to. Easy peasy!
Turned out okay, I think. Worth giving a go at any rate, a bit more satisfying than using the printed one (though as I said, I used that one myself for ages, so I'm not dissing it).
P.S. If you ever fancy doing some kind of Belgian gunboat, don't use the naval ensign on the site that Traveller linked to. It dates from the 1950s.