Paul - here is a quick sketch of what I was thinking. Kerf thickness will come into play on step #6 since the upper portion will settle lower because of the removed material during sawing. Your square will be offset unless your kerf is exactly the same width as your aluminum which is unlikely. Maybe using a very small hand saw or Exacto-Saw would work. I would use as small a kerf bladed tool as you can find. A table saw or cut-off saw would just consume all the material so you would have nothing left.
One possible way to rectify the offset, and I haven't tried this or seen it done, is to make a vertical cut from the compass point up to remove some material before you lay in the aluminum. This would narrow the "V" and possibly line the square back up. It would be a trial and error type of operation. Again, I haven't tried this but I just thought of it so maybe it will work. I'll be trying this concept sometime. This will end up narrowing the entire center blank so some thought may have to be put in to see if this modifies the thickness of the initial cuts into the blank ... not sure.
Lightly sand the mating sides of all 3 vertical pieces to ensure they are flat. You can skip this step if you used a table saw (but you lose a lot of material with the TS). Glue everything back up and let sit for a couple days.
Get some aluminum nails. Carefully drill a hole at the compass point. I would drill half way thru from opposite sides to ensure the hole is directly on the compass point ... unless your drilling is a lot beter than mine!
You are going to have to try this procedure a few times to see if you can create the effect you are looking for. It seems doable but there are perials waiting for you. Get some scrap wood and see how it goes and how you might need to modify your process. This could be a lot of fun! I may even try one myself.
Let me know how it goes.