HGTV's Alison Victoria, host of "Windy City Rehab," used a stunning faux plaster ... sleek contemporary mantels. Architectural salvage shops and yards also often have old fireplace frontispieces ...

The shelf supports are hidden, and it’s made of the same material as the lime plaster ... your fireplace, as shown in this cozy space from @timberfields. You can find chunky faux wood mantels ...