Hi. I take it you want the rigid arms rather than the normal flexible arms of a spider light? Here’s one similar https://www.e2contractlighting.co.uk/product/minimal-geometric-antique-brass-chandelier-cl-38765/

Try Crosswater. We're about to buy one of their Crosswater Infinity double vanities - you can configure them in various ways.

https://www.hem.com/collections/sofas-poufs Just check out their VaT on imports post Brexit (I was stung buying art in January from a Danish company!)

Given the "pattern" of the surface goes all the way through, that'd mean real stone/marble would have to be a full - and possibly thick - slab, milled down and then polished to the fluted surface. The price for that, and the substructure/installation cost for a real stone slab of that size and weight, is going to be in the range of "whatever - don't do it if that matters in any way". I mean, crazier things have been done in London for sure, and you'll find natural stone fabricators willing and capable to execute this. I wouldn't preclude a custom commission but agree with others, it's probably a form of large-format porcelain. Have you considered contacting the developer directly ?