What are some ways to represent a metallic 'Clang' or 'Clunk' sound when a metal door opens in a comic?

For metallic sounds, use jagged or sharp-edged lettering. Consider a font that looks like it was forged in metal. You can add small, sharp lines radiating from the onomatopoeia to suggest reverberation or echoing. Using metallic grey or silver colors for the letters can also reinforce the metallic nature of the sound.