Affordable. Sub 27g. Full Functionality. ModMouse.

The ModMouse is a fully modular and affordable ultralight mouse that doesn't compromise. Built around the more affordable Keychron M4 donor board ($70 USD), it delivers true ultralight performance with complete side button functionality at a more accessible price point.

After hundreds of hours of daily use and gaming—over 1 million clicks and 10km of travel—it continues to perform flawlessly.

What Makes ModMouse Different?

• Affordable: at 70USD, the Keychron M4 donor board is a more affordable options than others like the Logitech G Pro X(149USD) or the Pulsar x2v2(100USD)
• Side button support: ModMouse retains fully functional side buttons for productivity and gaming—all while staying under 27g.
• Ease of printing: Each piece has been designed with built-in support and no special filaments/printers are required.
• Modular Ergonomics: Swap between raised and flat triggers to tilt your hand into a natural position that helps reduce pronation and RSI. Customize side grips, textures, and colors to match both your aesthetic and needs.
• Wingtips: Each side grip features a wingtip finger rest to keep fingers off the mouse pad.

Print Settings & Materials

Must print at .12mm layer height for proper support tolerances.

Post-Printing

Wait until the prints have fully cooled before removing from build plate. Removing too early may cause subtle warping not visible by eye. Take care to limit flexing each part when removing and handling for the same reason. 

Note: Once installed it is very solid. The strength comes from the board itself with multiple contact points.

Support removal

The triggers and side grips have built-in support that must be removed before assembly.

1. Each trigger has a small tab to snap off where it fits into the frame. The small window in the top of the trigger should be removed as well. 
2. Each side grip has a support wall on the bottom that can be snapped off with ease. 
3. For the thumb side grip for the side buttons, flex each side as if clicking (without a board installed) until it snaps free and can more freely rotate along the spine.

Assembly Instructions

To start, follow the Keychron M4 disassembly guide. Only the 3 boards and 5 screws are required.

1. Prepare boards: Press the 2 main boards together. 
   1. Place the combined boards on the frame and use all 5 screws to secure board to frame.
      Note: Go slow in order to not stress the pegs. 
2. Assemble thumb side grip: Slide the small board with the side buttons into the printed side grip in the same orientation as it came with(bump facing down).
   Note: If the sideboard needs to be removed, use the included board removal tool to hook the exposed notch and give it a good pull.
   1. Test that each button can be easily clicked. If its stiff, remove the board with the removal tool and ensure both sides of the thumb grip can flex freely along the spine(see photos).
3. Install side grips: With the side grips ready, attach the side grips to each side of the frame. It should be a tight fit - the side grips should be touching the board at this point. 
   1. Connect the sideboard cable to the motherboard connector in the back left.
4. Install the mouse wheel holder: Slide the small piece over the mouse wheel axle until it reaches the daughter board surface.
   1. Give the mouse click a try. If the click is too tight, pull the mouse wheel holder up a tiny bit to give more clearance.
5. Install the triggers:  Push the triggers into place, making sure not to put pressure on the cutout.
6. Install skates: 5 skates are used, 1 for each finger pressure point. (See photos)
   1. 2 skates at the front for the triggers
   2. 2 skates on the ring+pinky finger side grip under where each finger rests
   3. 1 skate on the thumb side grip where the thumb rests
7. The mouse is now complete and can be used like normal.

Have fun!