OTS Guardian FFM Accessory Rail GoPro Mount

This is a simple and rugged GoPro mount designed for the OTS Guardian Full Face Mask using the OTS Accessory Rail System (sold separately). I created this for my own cold-water diving setup and wanted to share it for anyone who needs a reliable way to run a GoPro on the right side of the mask. The design focuses on practicality and stability in real dive conditions.

What It Is

A 3D printed slide-on mount that interfaces directly with the OTS Guardian Accessory Rail System. The GoPro sits just off the right side of the mask, close enough for stable footage while staying clear of the regulator ports and field of view. The design favors brute strength over elegance. It is not hydrodynamic and will introduce some turbulence in the water, but it stays put and does the job.

Why PETG

PETG offers excellent durability, toughness, and resistance to salt water. PLA will soften and degrade in marine environments, and while ABS or ASA can survive, PETG remains the easiest and most reliable option for divers who want strong parts without dealing with the printing challenges of higher-temperature materials.

My Actual Print Settings

I use the strength settings below:

• Heavy top and bottom shell count
• 15 percent gyroid sparse infill
• Monotonic top and bottom surfaces
• Generous paint penetration layers
• Rectilinear internal solid infill

These settings create a solid part that handles water movement, bumps, and rough handling without wasting unnecessary filament.

How It Locks in Place

The mount uses a set-screw retention system:

1. A nut sits inside the internal rail channel.
2. A screw threads through the mount and grabs the nut.
3. The screw extends slightly beyond the nut and seats into the notch on the OTS rail.
4. Tightening the screw prevents the mount from sliding up or down the rail during a dive.

This provides a positive mechanical stop instead of relying on friction alone.

Installation

1. Print in PETG using your preferred strength profile.
2. Insert a nut into the internal rail channel and run the set screw through to hold the nut in the channel. Do not over-screw.
3. Slide the mount onto the OTS Guardian Accessory Rail System on the right side of the mask.
4. Tighten the set screw until it engages the rail notch.
5. Attach your GoPro housing using the standard mounting bolt.

Once tightened, the mount remains stable throughout the dive.

Notes for Makers

This design is intentionally simple and brute force. It is strong and functional, but not elegant and not optimized for hydrodynamics. If you can design a sleeker or more streamlined version, I would genuinely love to see it. I will happily retire my design in favor of a better one.