Seiko Mod Watch Cases — Ultra Thin to 42mm, NH34 GMT-Ready

Both. Path A modifies an existing Seiko (cheaper, more disassembly). Path B builds from scratch on an LA case (full design freedom, simpler assembly). New modders usually start with Path A; experienced modders move to Path B.

The range runs from 33mm to 42mm. The heart of the line sits at 36mm — the size most of our platforms are built on — with 33mm and 34mm for smaller wrists, 38mm and 39mm in between, and a 42mm SKX007-family diver at the top. Each product page lists the case's exact dimensions, including thickness and lug-to-lug.

NH35 if you want a date. NH36 if you want a day-date. NH38 for a clean no-date or open-heart dial. NH34 for a GMT travel watch. NH70/71/72 are skeletal. All share the same Type M architecture and are interchangeable across the Lucius Atelier smaller-case lineup.

The Lucius Atelier Bauhaus 33mm Ultra Thin Edition is the thinnest NH-compatible Seiko mod case on the market at 9.93mm with a solid case back. The rest of the Ultra Thin lineup sits close behind.

| Case | Thickness |
|---|---|
| **Bauhaus 33mm** | 9.93mm |
| **Seikonaut 38mm** | 10.0mm |
| **1908 36mm** (NH34 GMT-ready) | 10.75mm |
| **SKX013 Diver 38** | 10.86mm |
| **Pilot 34mm** | 10.96mm |

For context, most Seiko mod cases on the market run 13–14mm thick. The Ultra Thin programme is an engineering effort to push the floor below 10mm while remaining NH-compatible.

Smaller cases (33–38mm) wear better on most wrists, slip under a shirt cuff, and let dial designs read at correct proportions. The LA smaller-case lineup spans seven cases from 33mm Bauhaus to 38mm SKX013 Diver, every one Ultra Thin Edition.