0p3n Case - Modular, Accessible, and Efficient PC Case Design

The 0p3n Case is a fully modular, open-frame PC case designed to make custom PC building more accessible, affordable, and adaptable -especially in a time of rising component and living costs.

At its core, the 0p3n Case focuses on maximum compatibility with minimal material use. The modular structure supports a wide range of hardware configurations, including ATX to ITX motherboards, ATX to SFX* power supplies, and varying GPU lengths, allowing builders to reuse existing parts rather than buying new ones.

Unlike many 3D-printed PC cases, the 0p3n Case is intentionally engineered to use very little filament, significantly reducing print time, cost, and waste while still maintaining structural rigidity. This makes it practical for hobbyists, students, and first-time builders who want a functional case without expensive materials or specialized tools.

Modular by Design

Each section of the case is designed as a standalone module, making it easy to remix or expand:

• Add support for a second GPU
• Modify airflow paths
• Integrate larger radiators (up to 360mm)
• Adapt the layout for custom cooling or future hardware

The entire design is fastened using approximately 20-30 (depending on the configuration) standard M2 × 10 mm countersunk screws, keeping assembly simple and low-cost. The model can easily be remixed to support other screw sizes if preferred. Motherboards mount using standard 7 mm motherboard standoffs, ensuring compatibility with commonly available PC hardware.

Designed for Makers

• Optimized for easy 3D printing
• Minimal support requirements
• Straightforward assembly
• Open-frame layout for easy access and maintenance

The 0p3n Case isn’t just a PC case-it’s a platform for experimentation, customization, and affordable PC building.

Assembly is easy:

1. Begin by aligning the motherboard plates with the holes of the motherboard
2. Screw in the 7mm standoffs to match your motherboard, and screw down your motherboard to the standoffs
3. Insert your io shield into the rear plate (optional)
4. Screw together the rear plate with the motherboard plates, so the motherboard aligns with the io shield
5. Screw together the front plate with the motherboard plates, matching it with the rear plate's orientation
6. Screw in your power supply to the rear plate using stand power supply screws
7. Screw in the psu brace (optional, but can help prevent some sagging)

As for the power button, I used a 19mm circular power button (similar to this one) and included a small bracket for that to attach to the front plate. This modular design means any button could be swapped out (or even use a spare keyboard switch), all that needs to be remixed is the power button bracket!

*SFX will require a ATX to SFX adapter plate which can be found on Makerworld. If there is enough interest, I aim to add a rear plate for SFX PSUs in the future.

OnShape project for remixes and more In-depth Guides to come…