Bondo issues

Well I have a couple ideas that may help. First one that comes to mind is a flowable polyester putty. apply a thin coat with the edge of your spreader, this sands much easier than bondo (ie 120g). It will fill your pinholes an small craters.

Second Idea, I have read on here a common way is to mix a runny batch of bondo with resin and apply that with a brush or spreader. (maybe someone can find you a good ratio. I have heard 2:1, 5:1)

Third Idea, assuming you are priming your enclosure, not knowing the kind of primer you are using I will go with what I am familiar with. A 2 part or 2K primer if applied in 3-4 medium wet coats will also fill these imperfections. If you see what looks like a little black hole just dab it with your finger tip while the primer is wet and it will fill the hole with primer. Try and do that in the 3rd or 4th coat, that way you will be able to sand out your finger print mark with no adverse effect on the finished paint job.

Now I am going out on a limb here, some may disagree with me here... You do not have to sand your bondo down to 2000g (of course this is if you are priming it..) If you are priming the enclosure 280-400 is the finest you want to go to get proper adhesion between primer and bondo. After you have primed than you may wet sand with 2000g before paint. (even 1200 - 1500 is sufficient) The important thing is a mechanical etch for the Primer/paint to grab onto. To fine and you will have runs and flaking paint. To course (say 600 or less) depending on color the sand scratches will show up in your paint.

Sorry for rambling...but I hope I helped

under the fleece is mdf, so is that still fine?? because just rapped the wood in fleece.. resined it, then covered that in bondo

Is your whole box MDF? did you just wrap it in fleece and bondo so you could paint it?

If you primed the box with high solids primer without the fleece and bondo you can still paint it to your desired finished. (you don't have to use fiberglass on a standard box). Though you could FG the flat board. (may be unecessary work)

If you were making contours etc. to flush mount your subs with the fleece than you have to cover it with the cloth or mat. The fleece and bondo are just going to shatter on you.

From here I do not know if you can take all the bondo off and still mat the fleece or not. you may just have to start fresh.

Do you have any pics of the box to better show what you are doing?