GRAM Slim
GRAM Digital Controllers
GRAM Slim
Overview
The GRAM Slim was an ultra-thin open-source leverless that pushed low-profile construction further than most commercial peers.
Hardware
Physical Characteristics
The chassis height of 11mm was achieved through a “floating” switch design, where the switches use the top panel as a mounting plate.
Materials
Frame: Injection-molded polybutylene terephthalate (PBT)
Top Panel: Depending on variant:
- Aluminum PCB
- Powder-coated aluminum
- Powder-coated aluminum with UV Printing (Genesis X2)
Bottom Panel: Depending on variant:
- Aluminum PCB
- Powder-coated aluminum
Button Caps: Injection-molded PBT, 24mm diameter
Switch Configuration
The controller contains 21 mechanical switch positions, all using Kailh Choc V1 switches mounted in PG1350 hot-swap sockets.
Compatibility
- Firmware: Pico-Rectangle on early revisions and HayBox on later GRAM Slim revisions
- Native support: Platform-fighter and GameCube-style setups, plus standard USB use on PC
- Connection: USB-C, with USB-C to GameCube and USB-C to USB-A cables included on retail units
- Notes: Compatibility varies by hardware revision because the firmware stack changed over the lifetime of the product.
In the Box
The controller was sold with:
- GRAM Slim controller (pre-assembled)
- GRAM neoprene soft case
- Braided USB-C to GCC cable (1.8m)
- Braided USB-C to USB-A cable (1.8m)
Optional Accessories
- Replacement button sets
- Alternative switches (Kailh Choc V1 variants)
- Printed aluminum top panels
- Replacement frames
- Hard-shell carrying cases
History
Open Source Release
On May 24, 2023, GRAM Digital Controllers published the complete design files for the GRAM Slim on GitHub under the GPL-3.0 license. The repository includes:
- STL files for frame and button cap printing
- Fabrication files for aluminum top and bottom panels
- PCB Gerber files
- Assembly documentation
- Template DXF files for panel customization
Version History
- GRAM1 - 5 units made
- Firmware: Pico-Rectangle
- GRAM-OF1 (formerly GRAMv2?) - 16 units made
- Firmware: Pico-Rectangle
- Firmware: Pico-Rectangle
- GRAMv2 (rectangle corner release?)
- GRAM Slim Smash v3
- Firmware: Haybox
- GRAM Slim Smash v3.4
- Firmware: Haybox
- GRAM Slim v4 - Screwless?
- Firmware: Haybox
Discontinued (2025)
- Production ceased
DIY / Open Source
Bill of Materials
Electronic Components:
- 21× Kailh Choc V1 switches (Red, Red Pro, or Whites)
- 21× PG1350 hot-swap sockets
- GRAM Slim PCB, designed by Quark
Mechanical Components:
- GRAM 24mm Choc Keycap Buttons (3D print from STL files or purchase)
- GRAM Slim Frame (3D print or purchase)
- Top and Bottom panels (order from fabrication service)
- 7× M5×0.8 8mm Low-Profile Socket Head Screws
- 7× M5×0.8 Round-Base Weld Nuts
Optional:
- USB-C to GCC cable
- USB-C to USB-A cable
Recommended Print Materials
Frame:
- LEDO 6060 resin
- Black resin
- PA12-HP Nylon
Button Caps:
- LEDO 6060 resin
- 8001 Transparent resin
Assembly Process
- Frame preparation (print or purchase)
- Insert PG1350 sockets into PCB
- Press switches into sockets
- Attach keycaps to switch stems
- Secure panels using M5 screws and weld nuts
- Flash firmware via USB
No soldering is required for switch installation.