Steam Box 5 Slim — BC250 Vertical Mini PC Case

IMPORTANT: enclosure is BETA and recommended for BC250 enthusiasts owning 3D printer, that are able to experiment, test and provide feedback (not to order it blindly for printing in 3rd party service providers, as some flaws may be discovered requiring fixing).

UPDATE: 07/10/2026 - I can't explain how, but previously uploaded models of lower and upper U-shells had bc250 fixation pattern mirrored. I never designed them that way, crazy. I replaced files thanks to user report. Hope not too many people wasted their filament with that glitch. 

UPDATE: 25SEP2026 - added alternative model to use 2x80mm fans for hot air exhaust instead of one 92mm.

Steam Box 5 Slim — AMD BC250 Vertical Mini PC Case

Steam Box 5 Slim is a compact custom 3D-printable enclosure designed specifically around the AMD BC250 board.

The original Steam Box 5 FAT was designed mainly for heavily overclocked or particularly “lucky” BC250 boards, where maximum cooling performance is the priority. It has enough internal space for the large JF13K cooler and a more aggressive cooling setup.

The Steam Box 5 Slim takes a different approach.

It is intended for the average BC250 user who wants a much smaller and cleaner enclosure while still maintaining good temperatures without extreme overclocking. It can also be a more budget-friendly build, as it does not require the large JF13K cooling solution used in the FAT version.

The BC250 is mounted diagonally inside the case, allowing the overall footprint to be significantly reduced while still providing enough space for the PSU, CPU cooler, VRM/VRAM cooling and case airflow.

Main Features

• Compact vertical BC250 enclosure

• Zero screws assembly concept

• Two-piece U-shell construction

• Sliding/dovetail assembly system

• Modular front mesh and fascia

• ID-Cooling IS-67-XT CPU cooler configuration

• Dedicated airflow for the BC250 VRM/VRAM area

• Arctic P12 Pro cooling fan

• Arctic P9 / P9 Silent exhaust fan

• Mean Well LOP-300-12 power supply

• Integrated Anker 4-port USB hub

• M19 front power button

• Rear AC power socket

• Perforated lower deck

• Removable Steam logo badge

• Designed with 3D printing, cooling and serviceability in mind

Required Hardware / Components

For the configuration shown in this project you will need:

• 1 × AMD BC250 board

• 1 × ID-Cooling IS-67-XT CPU cooler

• BC250-compatible CPU cooler mounting hardware

• Small heatsinks for the required VRM/VRAM components

• 1 × Arctic P12 Pro

• 1 × Arctic P9 or P9 Silent

• 1 × Mean Well LOP-300-12 PSU

• Required PSU connectors/wiring for connection between the LOP-300-12, BC250 and AC input

• 1 × M19 momentary push button

• 1 × Anker 4-port USB hub

• 1 × 3-pin 250 V / 10 A AC power socket (AC-17 type)

• Either:

  • 1 × approximately 120 × 120 × 10 mm aluminium heatsink, or

  • 1 × slim 80 mm fan

• Appropriate screws, wiring and small assembly hardware

Printing and Fitment Notes

The case was designed around approximately 0.20 mm fitting clearance for the sliding and interlocking parts.

On a well-calibrated modern printer this should provide a good fit, but older printers or machines with less accurate dimensional control may produce tighter sliding joints.

Do not force the parts together during assembly.

If a male dovetail or sliding section is too tight, lightly work the contact surfaces with Scotch-Brite or very fine abrasive material, repeatedly test-fitting the part until it slides smoothly. Removing a very small amount of material is much safer than forcing the joint and potentially breaking the printed part.

The same advice applies to the fascia rails and other sliding connections.

I recommend test-fitting the major parts before installing the electronics.

Cooling Philosophy

The Slim version is not intended to replace the maximum-performance Steam Box 5 FAT.

If you are running a heavily overclocked BC250 and want the largest possible cooling solution, the FAT version with the JF13K remains the better platform.

The Slim version is designed around a more balanced idea: smaller size, lower component cost and good everyday BC250 temperatures, provided the board is not pushed to extreme power and overclocking levels.

As with any BC250 build, final temperatures will depend on the individual board, power settings, fan curves, ambient temperature and the quality of the thermal interface and heatsink installation.

This is an enthusiast project built mainly for fun — non commercial activity.

Heat sinks options (few of a million options :-) ):

https://www.aliexpress.com/item/4000532648266.html
https://www.aliexpress.com/item/1005008976330401.html
https://www.aliexpress.com/item/1005007391616890.html
https://www.aliexpress.com/item/1005005202554577.html

Available contests