Space-Saving Luxe Staircase Design

I want a staircase that serves two directions in my home: one flight rising to the attic and a second flight dropping to the basement. The overall look must be unmistakably modern, but still feel luxurious.

Key design cues
• Treads, stringers and landing surfaces in premium stone (or a convincing engineered alternative) for a solid, high-end feel.
• A slim, clean railing—no visual clutter—incorporating integrated LED strips that wash light down both flights at night.
• Space-saving geometry is essential; I’m open to switch-back, helical or a hybrid configuration so long as building-code head-room and riser/run ratios are met.
• Please keep the underside visually light and, where possible, shape it so cabinetry or hidden storage can be added later.

Deliverables
• Concept sketches showing plan, elevation and how the up- and down-runs interlock.
• 3D renderings (preferred formats: .jpg and the native 3D file) that illustrate material, lighting and finish.
• Construction drawings with dimensions, tread/riser specs, railing details, LED placement and notes on required structural supports.

I’ll provide existing floor plans and ceiling heights once we start; I’d like the first concept round in a week, with revisions to follow.