If you asked me to build it I'd give you the option of showing me a much clearer example of what you want OR pay me upfront with the understanding I would take my best guess at how that sample would look had it been brought out into daylight and you take what I give you and never tell anyone where it came from.

In the later situation I would use steamed Beech sanded to 320 grit, use enough Golden Oak stain to bring it to deep yellow, apply black translucent wiping stain , apply one coat of clear with small quantity of dust size gold and copper flakes then topcoat with high gloss clear.

Bottom line , I figure experienced diy woodworkers might be challenged in matching under normal conditions and unpredictable with an obscured peek of original. Tell you how???????

Thanks Klem, sorry the pic is a little compressed (by Houzz) here is the uncompressed version https://leibal.com/wp-content/uploads/2019/03/leibal_wattle-house_golden_4.jpg it's only mildly better but might give a bit more detail.

I have seen a similar finished on steel using a pad to wipe apply all in one direct to give it that brushed brass look but I haven't seen it on wood.

Regardless of finish chosen this will have to be custom. This appears to be patinated brass (££££). Not made of sterling I would make it from wood and have an artist faux glaze it. Basically you mount a wood cleat on the three walls of the alcove and make a hollow box that slides over the timber. Terrible picture of pine shelves in my summer house built that way.

In the end I went for the easy route and hacked a desk...