Okay, here's where I'm at so far.
My first step was to find a curve that suited the size of the box. I created it on sketchup, but because its asymetrical it posed the problem of replicating it in real life. So I made zoomed in photocopies of the sketchup and pieced them together to give me a blueprint to work off.
This is the template I made for the router, which didn't work. But it gives you and idea of what each board will look like once I have the outside and inside cut. Of course this template doesn't include the modifications I make to most of the boards to creat the cone part of the box.
this is my first cut that I use as my sketching template for each board that follows. It gives you a visual of what the top of the box will end up like.
Creating the cone requires gradually changing the dimensions of the above template. This diagram is how I determined what measurements to use.
As you see here I'm about half way through the stack of plywood for the outside cuts. The cone part of the box is starting to take shape. So is the daunting task of getting that rough circle down to a smooth surface.
This side view gives you a glimpse at how the cone will blend into the box once its all sanded down.
And this is the 64000 btu electric furnace I just bought for my garage because the 16000 btu construction heater I've been using just isn't cutting it.
That's it for now. I'll get some more pics up once I've got all the boards cut and can show what the full box will look like.
Here's something I could use help with. I plan on making the front of the box about 2.5" thick so I can counter sink the sub in 7/8" and have 1.5" to mount it to. Any idea on how I'm going to cut a circle through 2.5" of solid wood?