What is a Seiko mod builder?

A Seiko mod builder is a tool that lets you select and preview Seiko watch mod parts — case, dial, hands, bezel, crystal, and bracelet — before buying anything. Assemble Watches does this for free, with automatic compatibility checking included.

Is Assemble Watches free to use?

Yes, completely free. No account needed, no paid tier. Assemble Watches is a community-built tool for Seiko modders.

Which Seiko platforms does the builder support?

The Assemble Watches builder currently supports NH35, SKX007, and SRPD-based builds. These cover the vast majority of aftermarket Seiko mod parts available today.

Does the builder check if parts are compatible?

Yes. As you select parts, Assemble Watches automatically checks compatibility — dial feet, hand tube sizes, case dimensions, and movement fit — and flags potential issues before you order anything.

Can I save or share my Seiko mod build?

Yes. Once you've assembled a build you like, you can generate a full parts list with vendor links and share the build with others via a unique URL.

Assemble Watches

Seiko Mod Builder

Assemble Watches is a free Seiko mod builder that lets you mix and match parts — case, dial, hands, bezel, crystal, and bracelet — visualize the result, and get automatic compatibility checking before you spend a penny.

Open the Builder →

Assemble Watches is a free Seiko mod builder and visualizer. It is free to use, requires no account, and checks NH35, SKX007, and SRPD part compatibility (case, dial, hands, bezel, crystal, and bracelet) before you buy anything. It is a planning tool, not a parts retailer.

What the builder does

Most modders buy parts based on guesswork, then discover fitment issues when everything arrives. The Assemble Watches builder solves this by letting you configure a complete build digitally first:

→Select a case, movement, dial, hands, bezel ring, bezel insert, crystal, and bracelet.
→See a real-time visual preview of the assembled watch.
→Get automatic compatibility warnings if parts won't fit together.
→Generate a full parts list with links to trusted vendors.
→Share or save the build via a unique URL.

Supported Seiko platforms

The builder currently covers the three most popular Seiko mod platforms:

NH35

The most popular movement for Seiko mods. Hacks, hand-winds, no date.

SKX007

The original Seiko diver. Discontinued but enormous aftermarket parts library.

SRPD / 5KX

Current production. Shares most SKX007 aftermarket parts.

Common questions

What is a Seiko mod builder?: A Seiko mod builder is a tool that lets you select and preview Seiko watch mod parts — case, dial, hands, bezel, crystal, and bracelet — before buying anything. Assemble Watches does this for free, with automatic compatibility checking included.
Is Assemble Watches free to use?: Yes, completely free. No account needed, no paid tier. Assemble Watches is a community-built tool for Seiko modders.
Which Seiko platforms does the builder support?: The Assemble Watches builder currently supports NH35, SKX007, and SRPD-based builds. These cover the vast majority of aftermarket Seiko mod parts available today.
Does the builder check if parts are compatible?: Yes. As you select parts, Assemble Watches automatically checks compatibility — dial feet, hand tube sizes, case dimensions, and movement fit — and flags potential issues before you order anything.
Can I save or share my Seiko mod build?: Yes. Once you've assembled a build you like, you can generate a full parts list with vendor links and share the build with others via a unique URL.

Try itOpen the Builder →Plan your build with automatic compatibility checking.LearnHow to Make a Watch →New to Seiko modding? Start here.ReadNH35 Movement Guide →Everything you need to know about the NH35.ReferenceGlossary →Plain-English definitions for every watch mod term.CompareWhat Is the Best Seiko Mod Builder? →How Assemble Watches compares to spreadsheets, retailers, and prebuilt services.

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