One-Hand Key Lock for Logitech MX Mechanical

A one-hand key lock that holds modifier keys down with a simple slide, allowing shortcuts like Ctrl+C, Ctrl+V or Alt+Tab to be typed with a single hand. Two versions are included: a Right Side version with 4 sliders and a Left Side version with 3 sliders, designed to fit the corresponding side of the Logitech MX Mechanical keyboard.

Who it helps

Designed for people who type with one hand or have reduced dexterity or grip, and can’t hold a modifier while reaching another key. Each key gets its own large slider:

Push → the key stays pressed, no finger needed.

Pull → the key is released and works normally.

Non-destructive

No opening, drilling or glue: the block clamps onto the front edge of the keyboard with two knurled knobs. The original keycaps stay in place.

Tested without the keyboard

I don’t own an MX Mechanical yet, so I printed a replica of the front-right end of the keyboard from the official dummy, fitted with the same switches and keycaps at the real height. The lock mounts on it exactly as on the real keyboard. Both left and right side versions were designed from the official Logitech dummy model and use the same mounting system.

Printing

PLA or PETG

No supports required

• Layer height : 0.15 mm

• Infill : 20%

• Walls (Perimeters) : 2

Assembly

Step 1: Slide the sliders into their channels from the front of the block (3 sliders for the Left Side version, 4 sliders for the Right Side version)

Step 2: Place the bar across the top of the block, behind the slider tabs

Step 3: Pass the 2 knobs through the bar and the block, then screw them 2–3 turns into the jaw

Step 4: Push the assembly against the front of the keyboard so the top rests in front of the 4 keys and the jaw lip slides under the edge

Step 5: Tighten the 2 knobs by hand until the block no longer moves

Step 6: Completed !