How do I get this finish?

[Alan m]

id make the wooden part a bit wider too. also id use a bearing guided spiral bit to bring the wood to the aluminium or to a known offset. sanding will ruin the wood

 

[mouppe]

In fact, having looked closer at the way the grain meets at the corners, I am absolutely certain this is a veneer. You'll also dampen vibration using MDF instead of solid wood which would be good for a turntable.

Richard.

 

[oradba69]

In fact, having looked closer at the way the grain meets at the corners, I am absolutely certain this is a veneer. You'll also dampen vibration using MDF instead of solid wood which would be good for a turntable.

Richard.

Thanx Richard, makes sense.

 

[stairman]

I'd mill everything very near finish thickness, dry clamp the entire assembly, mark for layout, and domino everything.  a clamping block "jig" for the 4mm aluminum, and you can cut right through, while registering everything exactly where you want it, cutting way down on the sanding problem.

-Luthiers often have "narrow" Widebelt sanders equipped for short stock,  perhaps you could find one who would flatten out your glue-up.
alternatively, that could be sanded out with a (hard) longboard (aka "hand-file").  use zirconia abrasive, and it will cut the aluminum like hot butter.

you might consider Afromosia or similar density wood to more closely match the density of the aluminum...

interesting project,  have fun and please take some pictures before, during and after 8)

-Kyle