Did you resin and fiberglass? Also I concur with what Jowe said, I believe that pep is the most important step in doing a pep project. A lot of people think " I'll just fix it in the bondo/molding stage" But there is only so much you can do in the final stages of a helmet like this.
As for the build, it looks okay. If you give us more details about the build, we might be able to help you fix it.
The pep model is only a guide. Sometimes you might sand down through the paper to get the right shape you need, thats why it's important to have plenty of glass on the inside. As far as the pinholes go that's from air trapped in the bondo. Just try and mix it as smoothly as you can but don't over mix it either. (every time you mix it you will introduce more air into it.) Stop mixing when the bondo turns a uniform color throughout then you're ready. Take it from me, I'm an auto body mechanic by day.
like kdub said, pinholes are from mixing. how many coats of resin/fiberglass did you apply? I usually do one coat in and outside of pure resin, then glass the whole thing inside, then another coat of pure resin inside, a bit of overkill, but this way I ensure that it won't collapse when I do the filler work
I have done similar to J0wE. Only I use casting plastic insead of resin. I brush a coat on the out side let it completely cure then brush a second coat on the outside. Once that has cured I slush a liberal coat inside before adding my fiberglass cloth. I then take my dremal and knock down all my pep lines before applying a thin coat of bondo. I will sand and repeat this bondo and sanding process till I have got it to the point that I can use spot filler. Then I wet sand and apply my primer.
I have to agree with the above. It looks like the areas between your pep lines are caving in. Did you spend enough time on the resin/reinforce stage? I used "Bondo" brand fiberglass resin. 2 full coats outside, 1 inside, then fiberglass cloth and another coat of resin inside. The finished product is so tough i can barely flex the sides of the helmet pushing with most of my strength.
Your pep looks fine, dont worry about it. How many layers of fiberglass did you use inside? I used 1 layer and experienced some severe warping so make sure you do at least 2-3 layers of glass.
The pinholes in the bondo are pretty unavoidable. Yes you can try mixing more carefully to avoid air in the mixture but in my experience you will always get some. They can be fixed with another thin layer of bondo or pick up some spot putty filler, thats what I used.
Make sure you are putting bondo on in thin layers too. If your layers are too thick it may not cure properly and you will begin to lose your original shape.
seconding the bit about thin, thiiiiiiin layers. My first helmet got absolutely buried in bondo and I wasted dozens of hours trying to make sense of it. I just started my second and by using paper thin layers I've managed to about finished half of it in a few days.