AC Hidden Blade — Brotherhood Style

The Brotherhood Style dual-action hidden blade, inspired by Assassin’s Creed, is built on my new CR-26 platform — a redesigned mechanism that’s more reliable, easier to use, and finally 100% 3D printable compared to the original 2023 version.

🎬 Full video guide (printing, assembly, setup): https://youtu.be/k-QvD69OD9E

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What’s New

The original 2023 design has been completely reworked from the ground up.
It keeps the same simple assembly — but fixes the biggest pain points and improves performance across the board:

• 100% 3D printable — can work without a cord, elastic band, or Velcro straps
• More consistent to print — a simple Flow Test before printing makes results predictable (no more guesswork)
• More durable — now features a firm blade lock in both positions
• More reliable — activation no longer depends on how fast you pull
• Shorter pull length — easier and more natural activation
• More comfortable to wear — improved ergonomics, repositioned mounts, and removable pads shaped to your arm
• No glue required — ready to assemble right after removing built-in supports
• Improved cover fit — sits much tighter than before
• Minimal blade play during operation
• Modular platform for multiple upcoming styles — follow my profile so you don’t miss new releases

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Lubrication

Testing showed that PLA mechanisms benefit from plastic-safe lubrication for reliable operation.
I’ll likely recommend this for future projects as well.

See the video for guidance: 00:54

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Optional Components

Recommendations for optional parts (cord, elastic ring, Velcro straps) are included in the ReadMe.txt.

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Dimensions

Largest part (Cover): 138 × 138 × 200 mm

If it's too tall for your printer, you can print it as two separate parts:
Optional_Parts --> Split_Cover_Bottom_Part.stl, Split_Cover_Top_Part.stl
Use filament offcuts to align the parts during gluing.

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Important Notes

• Do not remove the blade from the heatbed until it cools to at least 30°C, otherwise it may warp
• If you are using Ultimaker Cura, make sure “Print Thin Walls” is enabled before printing (you can find it via the settings search)
• I recommend tuning flow from the higher end downward, not the other way around.

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Notes on Operation

• Use gravity to your advantage — pointing the blade downward makes extension easier, and upward helps with retraction.

• In the fully printable build, the pull strap is reset manually until it clicks. If you prefer automatic return, you can add a rubber band (see recommendations in the ReadMe.txt).