Maybe you can get a machine shop to open it up for you a tad.

But back to paint. Last week when I was reconsidering the canvas white, I took some with no thinner and slopped it onto a piece of sheet metal I had so I could see the color. It was put on way too thick (to make sure I could see the color), and 6 days later I could easily scrape it off with my fingernail. Today I put it out on my deck in the sun. it was in the sun probably 8 hours or so, at between 80-90 degrees of ambient temperature. Now, it's unscratchable..

So anyone who has a running driving car, consider setting it out in the blazing sun, turn it every 5-6 hours, and that should help the hardness. I'll be holding off on any polishing until after my car's running and I can sun bake it for a day or two.

I know 69charger mentioned this before, just thought I'd remind people of it. It even works with unthinned paint that was globbed on way too thick as my little test demonstrates.