If you have any interest in making musubis at home, the musubi mold is worth the investment (and at $10, it’s not really much of an investment) to ensure the rice is tightly compacted.

【Sushi Making Kit】Contains 1 pc musubi maker and 2 pcs triangle onigiri mold (pink & beige) with 2 pcs small rice paddle, which are made of thick, highly durable food grade plastic material ...