Technically, the 3DS version stores inventory data in a structured binary format, similar to PC’s .plr files but with platform-specific offsets. Early editors were rudimentary, requiring hex editing; later, community-developed GUI tools emerged, often using precomputed hash values to avoid save corruption. This process, however, required a homebrewed 3DS—a legal gray area that voids warranties and risks console bans from Nintendo’s online services. Moreover, careless editing could render a save file unreadable, erasing hundreds of hours of progress. Despite these risks, the allure of spawning a full set of Solar Flare armor or a stack of 999 Platinum Coins proved irresistible to some.
Since you can't get Journey Mode on 3DS, consider purchasing Terraria on PC or Switch . On PC, the Celebrationmk10 seed or Journey Mode lets you duplicate items instantly. This satisfies the "inventory editor hot" urge without hacking your hardware.