The concept itself is fine.
For the surname, I would advise something different. "Gashapon" or "gachapon" are words that don't actually mean anything; it's onomatopoeia, and doesn't really express anything about your character like a Raen surname should.
The surnames of Raen commoners would be related to their profession. With that in mind, where did your character learn to make things? Were they apprenticed under someone before learning about clockwork and mechanics along the way? If they're self-taught, what was their family's profession?
For example, if your character was originally trained as some kind of metalsmith, then here would be some surnames to use:
Kazarishi (錺師) - Jeweller
Hakuuchi (箔打) - Metal foiling and striking i.e. a goldsmith.
Shirogane (白銀) - Silver
Akagane (赤金) - Copper
And etc.
For the surname, I would advise something different. "Gashapon" or "gachapon" are words that don't actually mean anything; it's onomatopoeia, and doesn't really express anything about your character like a Raen surname should.
The surnames of Raen commoners would be related to their profession. With that in mind, where did your character learn to make things? Were they apprenticed under someone before learning about clockwork and mechanics along the way? If they're self-taught, what was their family's profession?
For example, if your character was originally trained as some kind of metalsmith, then here would be some surnames to use:
Kazarishi (錺師) - Jeweller
Hakuuchi (箔打) - Metal foiling and striking i.e. a goldsmith.
Shirogane (白銀) - Silver
Akagane (赤金) - Copper
And etc.
