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Seikonaut Watch Case - 36mm

ONLY 4 main components are needed to complete a watch.
Watch Case
Rotor (optional)
Movement Holder (optional)
Tweezer (optional)


  • For a complete watch, select your (1) Dial, (2) Hands and (3) Movement.
  • To decorate movement, select your (4) Rotor (optional).
  • To have watch assembled, select (5) Assemble Watch. Please note that assembling the entire timepiece requires 2 to 5 business days prior to shipping.

Engineered by us and made exclusively for us with quality assurance by ISO 9001 Certified manufacturers.


Rejoice for those who like it small, the first ever Seikonaut @ 36mm! Including the side notches and crown, it goes up to 40.5mm and 43mm, respectively. Thus, giving this 36mm case a 40mm presence on wrist. Small, yet a huge statement.

Additionally, you will get an extremely crystal clear view of the dial and hands you would think there was no crystal in place. This was achieved by having both the outer surface and inner surface of the sapphire crystal coated with clear anti-reflective coating, also known as double sided AR coating. A simple procedure that brings new joy to visually appreciating your own mods.

Together with an integrated bracelet designed specially for this case.

**Designed to fit all of our dials (28.5mm) and original NH movements (grey dial holding spacer). Not suitable for GMT NH34 movement.
    1. Quality Swiss Production Quality, ISO 9001 Certified
    2. Case Material 316L Stainless Steel
    3. Case Diameter 36mm, 40.5mm with side notches, 43mm with crown
    4. Case Thickness 12.2mm
    5. Lug to Lug 43mm
    6. Lug Width 14.1mm
    7. Caseback Screw down, Clear Sapphire
    8. Crown Screw down
    9. Crystal Flat Sapphire with Double Sided Clear Anti-Reflective Coating
    10. Crystal Size 28mm x 1.5mm
    11. Water Resistant 200m / 20atm
    12. Fit Wrist Circumference 13cm to 20cm (Additional links can be provided for bigger wrist size)
    13. Fit Movements NH35, NH36, NH37, NH38, NH39, NH70, NH71, NH72
    1. 1x Watch Case (Inclusive of sapphire, crown, caseback, bracelet)

    All photos of watches with modification parts are for illustration purposes only and are not included with modification parts purchased.

  • Recommended Mods With:

    1. Swiss Super-LumiNova® BGW9 Hands
    1. A Complete Guide On How To Mod Your SEIKO Watch Dial And Hands (Includes Photos & Video)
    2. Learn about fitting dials with four dial legs

Customer Reviews

Based on 8 reviews
Drewe Mitchell (Sydney, AU)
Using this mod part for: Aftetmarket case
Green Seikonaut

Amazing case, looks phenomenal 👌

Mr.T (Tokyo, JP)
Using this mod part for: Aftermarket cases。。。
Best watch case!

I felt that the case of the previous GS was not good, but this time it was improved!

R. (Geneva, CH)
The watch I’ve been looking for for ages

I litterally found the perfect watch that I’ve been looking for after years. A nicely sized watch with the amazing Gérald Genta inspired look that suits my 16.5 cm wrist perfectly. The ability to choose every single element, from the dial to the hands, is a big plus. Furthermore, the watch was shipped extremely quickly after my order, and Adriel replies to e-mails very fast and is a very nice person. I am very satisfied with my purchase and will definitely order more in the future. Cheers from Switzerland !

Rex Ng (Central, HK)
Using this mod part for: New build
Excellent case and dial

The parts fit perfectly without issues and it looks gorgeous. The only improvements I'd like to see are the inclusion of bracelet half links and perhaps a lighter-coloured dial to match the true Tiffany blue.

Mauricio Aguiar (Cincinnati, US)
Awesome and reasonable size Nautilus option

Very happy with my build. I got inspired adored seeing a YouTube video (SVK Watches) and couldn’t help myself but to order one. Fast shipping and great quality products.

JT (Petaling Jaya, MY)
Using this mod part for: Seikonaut build from scratch
Perfect case size!

The availability of a smaller 36mm case was the reason I decided to put together a seikonaut build. Fits my wrist perfectly since the lug to lug wears bigger.

The case finishing and quality is great. Bracelet is comfortable.

Adriel also responded really quickly to a question that helped out a beginner modder like me.

I did end up using a different dial which was more muted that the Turquoise dial available.

D. (Triesen, LI)
Using this mod part for: Ground up build
Gorgeous case, great quality

The bracelet is comfortable and feels quite heavy and premium. Beautiful finish on the case and overall really good quality. It does wear a bit bigger than the 36mm might suggest, but i suppose thats in those Nautilus style cases‘ nature. Can recommend!

Simon Kuznetsov (Dubai, AE)
A good quality case set for the price!

I was pleased to find this case set with an appropriate bracelet. It’s stated at 36mm but the case is actually more like 40mm, quite a difference, but still a better design than the last one. Check out my in depth video review here: Seiko-Naut Tiffany Blue 36mm-40mm! Lucius Atelier Nautilus Style Parts Review

Judge.me YouTube video placeholder