Is each cell purely exponential? What's the flare rate?
When I got my 1505/288c combo I fell in love with multi-cell horns, that's what pushed me down the road of making my own. I'm wrapping up a few house related projects currently and planning to start making my own multi-cells this winter.
My plan is to make a few templates from baltic birch, or maybe even ~1/2" aluminum, then use a pattern bit on my router table to create the segments.
I would like to create a few throat adapters, 1", 1.4", maybe even 2", likely will start with 1.4" so I can use 288's.
Very cool to see how you tackled this!