u/Accomplished_Week731

I'm making a plug for a two-piece mold right now and had a question about filling low spots.

The part is already glassed, has fairing compound on it, and has a coat of Awlgrip epoxy primer. I didn't do a great job sanding out some of the low spots with the fairing compound, and I thought the primer would be thick enough to flatten them out, but I was wrong.

I'm out of fairing compound and was planning to thicken epoxy with microballoons to fill the low spots, but I now have a lot of clean dust from sanding the Awlgrip and I'm wondering if I could use that in place of the microballoons.

Has anyone done this? Microballoons are obviously cheap, but I'm running low, and I just want to finish this plug.