A metal cupcake pan bottom of stainless kitchen sink...put a few tea lights in pan. Space candles as needed.
Put a metal cookie tray that overlaps the sink...leaving air gaps along sides. The tray got warm pretty quickly and it was perfect for keeping our mugs of coffee/cocoa warm in a cold room when the power went out. The tea lights last for hours. CAUTION: Tray can get HOT depending on number of candles and an open flame is a fire hazard...the more candles, the more heat.
We positioned the tray upside down thinking it would collect the heat more evenly underneath....not sure if that matters or not.
Might try this when we have a party if we need something to be kept warm...love not having to store another warming tray.