Pepakura materials question

Hi,

I've made a couple of pepakura props in the past and have just finished the paper/card construction for my next, a full helmet modelled on the Machine56 Bonehead helmet.

I have two queries.

I saw someone using a fiberglass cloth, rather than material, material, and have yet to find anywhere selling it. I usually use the fiberglass sheeting you get at car repair shops and haven't managed to Google anything other than boat repair kits. The stuff I saw seemed a lot more user friendly.

The other query is what filler is favourite. I have been using Isopon P38 which is another car repair tool, probably the closest thing to the US's Bondo brand. I have applied this thinly, thickly, repeatedly, and in varying combinations, and never get a lovely smooth finish. What am I doing wrong? Would using a pre-mixed wood filler give me a better result? I can't work out what I'm doing wrong, the last thing I used went on really thinly and spread really thinly in layers and I still didn't get the finish I wanted no matter how much I sanded.

Thanks in advance if you can point out what on earth it is I'm doing wrong.

At the beginning of the year I had a go at my first Pep. I got asked a few questions on how I did things, here's the thread, hope it helps

http://www.therpf.com/showthread.php?t=253505