Apple peripheral maker Pad & Quill has a new coaster made with 'American Full-grain leather' it's selling for $20, though you could just buy one (or a set) with the same 4-inch dimensions on Amazon. If you wanted a more robust solution, MERES is selling both a regular aluminum stand for and one that's wall-mountable for $43. All could, in theory, protect your wooden furniture, assuming you don't have a plastic table or granite countertop to rest your HomePod instead, since users haven't reported it marking up on any other material.