Ah, "precision" it ain't, @ALB but functional it is. Here's how it looked when I used it...
—and this a.m. as I gussied it up. Trimmed the edges and took it apart, then glued it all back together and screwed and clamped it.
Now there's another MDF cover piece at the far end, glued with construction adhesive and screwed. Last thing I'll do as bore a big hole through the end. Then I'll file and sand it smooth and paint it.
And NO I'm not gonna drill a whole bunch of lightening holes.