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new to forum, fiberglass help... smoothing things out

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  • new to forum, fiberglass help... smoothing things out

    I recently made a fiberglass box for my Mazda MP3 (coincidence?). The structure turned out very well and I am happy with it. It fits liek a glove in the corner of my car. I am wanting to paint it, but it kinda sorta has a lumpy look to it. I want a piano finish but cant get the lumps out. I sanded the whole thing down real good and applied body filler, but I think i did it wrong. I pretty much sanded off all the filler and it only remains in the small holes. What is the correct way to apply body filler to fiberglass and get rid of the lumps?

  • #2
    You have the process correct. You just need to keep filling and sanding. It is not a quick process with such complex curves as you have. You will end up sanding most of the filler off. That is what you want. Thin layers are better.

    Keep filling and sanding. Then use a glazing putty to finish it off.

    Or, you have the rough shape you want, take it to a paint and body shop and have them finish it for you.


    • #3
      looks a lot like the first stealth box that i tried to make! (for a mazda 3 nontheless). 2 things for you...

      First- a little off topic but what size sub is that? Looks like a 10 or a 12 from that pic... Just a word of advice-i kept my stealth box for maybe a month because I had a 12" sub with a box that ended up just being way too small to do the sub any justice...

      Also, in regards to sanding and making it smooth-have you considered just carpeting it? I thought about it for a while and opted for carpeting for a few reasons. First, I realized quickly that there was going to be a HUGE time investment to get it perfect (not discouraging spending time but just evaluate whether or not it's worth it). Second I looked at the fact that this will be in my trunk and i throw stuff back there all the time-a glossy finish would quickly turn to ****. And lastly, my goal when making the box was to have a stock, stealth look and carpet was perfect for that. Also it's very forgiving with lumps!


      • #4
        maybe i shudda had someone close this thread cause i posted on similar right after. im finished with the box as of now, look for my only other post in the fabrication section and tell me what you think