FW12 Core – Modular Case for Framework Laptop 12 Mainboard

FW12 Core – Modular Case for Framework Laptop 12 Mainboard

What happens to your old mainboard?

Framework laptops are made to be upgraded, and every upgrade leaves a fully working mainboard behind. The Laptop 12 mainboard is a complete computer: CPU, RAM slot, SSD slot, Wi-Fi, four USB-C ports and its own fan. It just needs a safe home.

FW12 Core turns that spare mainboard into a slim 19 mm desktop PC, media box or home server. It keeps what makes Framework special: your expansion cards still slide in and out like they did in the laptop. If you have a Laptop 12 battery, the optional UPS module plugs it straight into the mainboard, so your server keeps running through a power cut.

The case is modular. Start with a minimal enclosure, then add card bays or the battery module whenever you like. Every part prints flat without supports, and the only hardware is a few heat-set inserts and screws.

Three ways to build it

1. Minimal – direct USB-C
Core base, core lid and front cap. The four USB-C ports stay reachable through openings in the side walls, so you can plug USB-C cables in directly.
Size: 241 × 126 × 24 mm (with feet).

2. Expansion card edition
Add the left and right card wings. Each wing holds two standard Framework expansion cards: USB-C, USB-A, HDMI, DisplayPort, Ethernet, storage and so on. The cards line up exactly with the mainboard's ports and plug in with a click.
Size: 287 × 126 × 24 mm, about the width of the original laptop.

3. Home server with UPS
Replace the front cap with the UPS module. The Framework Laptop 12 50 Wh battery sits directly against the mainboard and connects exactly as it does inside the laptop. The board charges it from USB-C power and switches to it automatically when the power goes out. The battery also keeps the BIOS clock and settings alive.
Size: 287 × 216 × 24 mm.

Features

Secure, self-aligning mounting

• The mainboard is held by its own captive screws, the same ones used in the laptop.

• Each mounting boss has a locating nub that drops into the counterbore under the board's standoff, so the board centres itself as you lower it in.

• Heat-set inserts in the bosses give a strong, reusable thread.

• A fifth mounting point at the front supports the board edge.

Printed power button

• The on/off switch on the mainboard is pressed through a flexure built into the lid. It is a thin, springy tongue with a plunger underneath.

• No extra parts, springs or glue are needed.

• The plunger rests 0.3 mm above the switch, so the lid never presses it by accident.

• An engraved ⏻ symbol marks the spot.

Built around the board's cooling

• The mainboard's blower fan draws air from both sides and blows it out through the heatsink fins.

• The lid has a hex grille directly above the top fan intake.

• The floor has a matching hex grille under the bottom fan intake, and the feet keep a 5 mm air gap underneath.

• The back wall has an exhaust grille, about 70 % open, placed directly behind the heatsink fins.

• Extra convection slots in the lid, floor, back wall and front cap let the RAM, SSD and power circuits breathe.

• No extra fans are needed.

Expansion card wings

• Guide tunnels align each card's USB-C plug precisely with the mainboard port.

• Thumb notches at the top and bottom of each bay let you grip a card and pull it out.

• Chamfered entrances make insertion smooth.

• The wings slide onto the sides of the case on three dovetail rails each, and the lid locks them in place.

UPS battery module

• The battery sits in a ribbed tray and slides back into the mainboard connector.

• A printed lock bar fills the gap in front of the battery so it can't back out.

• A screw-down lid covers the battery and carries an engraved battery icon.

• The tray and battery are kept at the front, away from the warm exhaust at the back.

Practical details

• Keyhole slots in the floor let you hang the case on a wall.

• A cradle on the floor holds an ML1220 RTC coin cell for builds without the main battery.

• Removing four screws opens the lid for RAM, SSD and Wi-Fi upgrades without taking the board out.

• The lid's overhanging edges lock every module in place, so four screws hold the whole case together.

Files

All files are already in print orientation, and each fits on a 250 × 210 mm bed.

If you're not building the UPS version, skip the UPS file and delete the lock bar from the small-parts plate in your slicer. If you're not using expansion cards, delete the wings. Your slicer can split any plate into separate objects.

Print settings

• Printer: 250 × 210 mm bed or larger (Prusa MK4 / MK4S / Core One, Bambu Lab A1 / P1 / X1, and similar).

• Material:

  • PETG or ASA for the base and both lids. Warm exhaust air passes through the back wall, and PETG handles repeated presses of the flexure button better than PLA.

  • PLA is fine for the wings, front cap and lock bar.

  • TPU makes grippy, quiet feet; PLA or PETG feet work too.

• Layer height: 0.2 mm.

• Perimeters: 3.

• Infill: 15–20 %.

• Supports: none.

• Bridges: the card openings in the base and the wing tunnels bridge 30 mm. Default bridge settings handle this; lower the bridge speed if your printer sags.

• Colours: a dark body with bright wings and cap looks great. Orange is a nice nod to Framework.

Hardware

Optional:

Tip: check the thread on your board's captive screws before buying the small inserts, and match the inserts to it.

Assembly

1. Install the heat-set inserts

• Press the five M2 inserts into the tops of the five mounting nubs in the base. They must sit flush with the top of the nub; don't push them deeper. The captive screws only reach about 2 mm into the insert, so a flush insert is what gives them full grip.

• Press the four M3 inserts into the holes in the top of the thick side walls.

• If you're building the UPS version, also fit four M3 inserts into the UPS tray walls.

• Use a fine soldering-iron tip and moderate heat.

2. Fit the feet

• Press the printed feet into the holes in the floor: four in the base, plus two in the UPS tray.

• If a foot is loose, add a drop of glue. Rubber bumpers can go in the same spots instead.

3. RTC cell (only if you are not using the main battery)

• Place the ML1220 cell in the round cradle at the front-left of the floor.

• Route the lead forward through the notch in the cradle, up in front of the mainboard's front edge, and plug it into the small 2-pin RTC connector near the battery connector.

4. Install the mainboard

• Hold the board with the components (RAM, SSD, fan) facing up and the heatsink fins toward the back grille.

• Lower it straight down; the locating nubs drop into the board's standoffs.

• Tighten the captive screws with a T5 Torx driver until snug. Laptop-level torque isn't needed.

5. Attach the card wings (optional)

• Hold a wing above the side of the base, line up its three dovetail rails with the slots, and slide it straight down until it sits flush with the bottom of the base.

• Repeat on the other side.

6. Fit the front module

• Front cap: slide it straight down into the two dovetail slots at the front of the base.

• UPS module:

  1. Slide the UPS tray down into the front dovetail slots.

  2. Lay the battery in the tray about 5 mm forward of its final position.

  3. Gently push it back toward the mainboard until the connector mates.

  4. Drop the lock bar into the gap in front of the battery. It should fall in without any force.

  5. Do all of this before fitting the core lid, because the lid's front edge overhangs the battery's path.

7. Close the lids

• Place the core lid so the power button (⏻) is at the back right, directly above the mainboard's switch. Fasten it with four M3 × 6 mm screws.

• If you built the UPS module, fasten the UPS lid the same way.

• The lid's overhanging edges now lock the wings and front module in place.

8. Check the power button

• The mainboard must not turn on while you tighten the lid.

• A light press on the ⏻ tongue should switch it on.

9. Insert your expansion cards

• Slide each card into a bay until the USB-C plug seats with a click.

• To remove a card, grip it in the thumb notches and pull it straight out.

Using it

• Power: plug a USB-C PD charger into any port, or into a USB-C expansion card. Press ⏻ on the lid to turn it on.

• Running without a battery: if the board won't start on USB-C alone, look for a standalone / no-battery option in the BIOS.

• Cooling: keep the back exhaust grille clear, and use the feet so the fan can breathe from underneath.

• Wall mounting:

  • The two keyholes are 190 mm apart.

  • Use screws with a head of 7.5 mm or less and a shank of 4 mm or less, left about 8 mm out from the wall.

  • Hang the case with the exhaust (back) side facing up so warm air rises out.

• Upgrades: unscrew the lid to swap the RAM, SSD or Wi-Fi card. The board stays mounted.

• Ideas: media centre, home server, NAS front-end, Home Assistant hub, retro gaming box, silent office PC, or a thin client behind your monitor.

Tips and troubleshooting

• The board turns on when the lid is tightened. Lightly sand about 0.2 mm off the tip of the plunger under the lid.

• The button feels loose or doesn't click. Make sure the lid is screwed down evenly on all four corners.

• The wings are too tight or too loose on the dovetails. Tight rails can be eased with fine sandpaper. Loose wings are still held by the lid overhang once it's screwed down.

• A card doesn't sit perfectly flush. Card faces may sit up to about 2 mm proud of or recessed from the wing; this is cosmetic. The USB-C connection always fully seats.

• An insert went in crooked. Reheat it and straighten it before the plastic cools.

Battery safety (UPS module)

The Framework Laptop 12 battery is a lithium-ion pack designed to live inside a laptop.

• Print the UPS parts in PETG or ASA.

• Never use a swollen, dented or damaged battery.

• The lock bar only fills a gap. It must drop in without force and must never squeeze the battery.

• Keep the case away from heat sources and direct sun.

• This is a hobby enclosure, not a certified battery housing. Use common sense.

Technical details

For remixers, these are the key mainboard positions, taken from Framework's official reference files:

• Mainboard: 219 × 119 × 6.75 mm overall, with a 1.0 mm PCB.

• USB-C ports: four ports on the short ends, two per side, 40.6 mm apart.

• Power switch: a small top-push tactile switch on the component side, near one short end, just below one of the USB-C ports.

• Mounting: five mounting points with captive screws. Each has an 8.2 mm standoff with a 5.6 mm counterbore underneath.

• Fan: a dual-inlet blower fan with top and bottom intakes. Exhaust exits along one long edge through the heatsink fins.

• Battery: the 50 Wh battery sits directly against the mainboard's front edge and connects by sliding toward the board.

Case design values:

• Mainboard PCB rests 7 mm above the case bottom.

• 3.5 mm air gap under the board.

• 3.7 mm air gap between the top of the fan and the lid.

• 1.8 mm side clearance.

• 0.25 mm dovetail sliding clearance.

Credits

Designed around the official Framework Laptop 12 Mainboard, Battery and Expansion Card reference files published by Framework Computer Inc. under CC BY 4.0.

Give your old mainboard a second life, and share your make. I'd love to see where yours ends up.