The circuit board sets the dimensions
The starting point is the board's STEP file from the ECAD software, for example KiCad or Altium. It shows the board outline, mounting holes and component heights, and it decides the internal dimensions of the enclosure. We add clearance around the board edge, usually 0.5–1 mm, so the board can be fitted even when enclosure and board tolerances go in opposite directions.
Connectors such as USB-C, RJ45 and screw terminals are placed against the walls, with cut-outs that follow the connector collar. Tall components, such as electrolytic capacitors and inductors, need clearance to the lid. If there is no 3D file, we make a simplified model of the board from dimensions and photos, including the components that affect the enclosure. We also add openings for programming headers and test points that need to be reached during development.
We also check for collisions across the whole assembly: board, enclosure, lid, screws and cables. This catches mistakes that would otherwise only show up at assembly. Examples are a capacitor touching a rib in the lid or a connector that cannot be reached with the cable plugged in. A cable with a straight plug can need far more room than the connector on the board.
Screw bosses, guides and assembly
The board is fixed on screw bosses that are tied to the wall or base with ribs, so they do not snap off during assembly. For self-tapping screws in plastic, the hole is sized to the screw manufacturer's recommendation, and the boss outer diameter is roughly twice the screw diameter. When the enclosure will be opened often, we choose brass threaded inserts that are heat-set or pressed in.
The lid is located by a lip or a groove so it sits correctly before the screws are tightened. Snap fits work well for lids that are rarely opened, but the material must tolerate the strain. We also think about the assembly sequence: the board must go in without trapping cables, and screws must be reachable with ordinary tools.
Buttons that are pressed through the enclosure can be made as flexible tongues in the same material or as separate buttons with their own guide. For LEDs we design light pipes or a transparent window, so no open holes are needed in a sealed enclosure. Markings and symbols can be engraved or embossed directly in the surface.
IP-rated enclosure and sealing
The IP rating under IEC 60529 describes protection against solid objects and water. IP54 means protection against dust and splashing, IP65 withstands water jets from any direction and IP67 temporary immersion. A higher rating needs a well-thought-out seal and fewer openings, so we always ask where the product will be installed before the rating is decided.
An O-ring in a groove around the edge of the lid is the most common solution. The groove is sized so the ring is compressed by roughly 20–30 per cent and fills no more than about 85 per cent of the groove. Cable entries are designed for cable glands with metric threads, such as M12, M16 and M20. Buttons and displays are sealed with a membrane or gasket. A printed enclosure rarely reaches the same tightness as a moulded one, and we say so clearly in the quote.
The seal must also survive assembly and disassembly. A lid with an O-ring needs enough screws to give even pressure all round, and the screw spacing is matched to the stiffness of the lid. A flexible lid with few screws bows out between them and lets water in where the pressure is lowest.
Heat and ventilation
Electronics tolerate heat less well than the plastic around them. We start from the power dissipation and decide whether the enclosure can rely on natural convection or needs ventilation openings, a fan or a heat sink through the wall. Inlets are placed low and outlets high, so warm air rises out.
In a sealed enclosure, heat can only leave through the walls. An aluminium heat sink or a larger housing may then be the answer, and we design the connection between component and cooling surface with a thermal pad. Ventilation openings are shaped as louvres or narrow slots, so fingers and tools cannot reach live parts.
Outdoor enclosures can suffer from condensation when the temperature changes. A pressure equalisation vent lets moisture out but keeps water out, and we add it as a standard threaded component. Dark enclosures in direct sun also get much hotter than the surroundings, which affects both the electronics and the choice of material.
Electronics enclosure design – from prototype to production
We print the first version of the enclosure in PETG or ASA with a wall thickness of 2–3 mm. You can fit the board, try the connectors and test the unit in its real environment. We then adjust the same parametric model, and changes to the board carry through to the enclosure without redrawing everything. If needed, we print several lid variants at once, so different seals or button solutions can be compared side by side.
Before production the model is adapted for injection moulding with uniform wall thickness, draft angles and ribs – read more under design for injection moulding. For smaller runs, a printed enclosure in ASA or PC may be enough all the way. We describe sensible tolerances against the board in the guide tolerances for CAD drawings, and the full development chain under product development and prototyping.
Guide values for enclosure design
| Feature | Guide value |
|---|---|
| Clearance between board edge and inner wall | 0.5–1 mm all round |
| Clearance between tallest component and lid | at least 1–2 mm |
| Screw boss, outer diameter | approx. 2–2.5 × nominal screw diameter |
| Wall thickness, moulded ABS or PC | approx. 1.5–2.5 mm |
| Wall thickness, 3D printing (FDM) | approx. 2–3 mm |
| O-ring, static axial seal | compression 20–30 %, groove fill max. approx. 85 % |
| IP54 / IP65 / IP67 (IEC 60529) | dust-protected + splashing / dust-tight + water jets / dust-tight + temporary immersion |
| Draft angle on walls (injection moulding) | at least 0.5–1°, more on textured surfaces |
| Cable gland | metric thread, e.g. M12, M16, M20 |
Guide values for common plastic enclosures. Final dimensions depend on material, manufacturing method and component tolerances.
What we need from you
- The board's STEP file from the ECAD software (KiCad, Altium etc.)
- Board dimensions, mounting holes and tallest components if there is no STEP
- List of connectors, buttons, LEDs and displays that must be reachable from outside
- Environment: indoors or outdoors, dust, water, temperature and the required IP rating
- Power dissipation or current draw to assess heat
- How the unit is mounted: on a wall, DIN rail, desk or handheld
- Expected volume: prototypes, small batch or injection moulding
Typical projects
- Enclosure for a battery-powered IoT sensor
- Outdoor box for a weather station
- Handheld meter with display and buttons
- Junction box for DIN rail
- Housing for a Raspberry Pi or Arduino project
- Motor controller enclosure with heat sink
- Front panel with cut-outs for connectors and LEDs
- Charger holder and battery box
- Sealed enclosure for marine electronics
- Cover for an alarm or access control system
What affects price and lead time
- Number of connectors, openings and buttons to be sealed
- IP rating requirement and choice of sealing solution
- Whether the board exists as a STEP file or has to be modelled
- Thermal management with ventilation or a heat sink
- Adaptation for injection moulding with draft angles and a parting line
- Number of prototype rounds before the design is frozen
What you get
- Enclosure and lid as an assembly with the circuit board
- Collision check between enclosure, board and cables
- STEP for the toolmaker and STL or 3MF for prototypes
- Drawing with critical dimensions, seal grooves and tolerances
- Bill of materials with screws, inserts, O-rings and cable glands
- Printed prototypes (optional)
Frequently asked questions
Can you design an enclosure for an existing circuit board?
Yes. Send the board's STEP file or dimensions and photos. We design the enclosure around the board and check that connectors, buttons and screws have clearance.
Can a 3D-printed enclosure be waterproof?
It can be splash-proof and, with the right design, cope with a fair amount of water. Printed walls can let moisture through, though, so for IP67 and long-term outdoor use we often recommend injection moulding or a sealed surface. We assess each case individually.
Which material suits an outdoor enclosure?
ASA resists UV light and temperatures up to about 90 °C and is a good choice for printed enclosures. Moulded outdoor enclosures are often made in PC or PC/ABS. PLA should be avoided outdoors.
What does IP65 mean?
IP65 under IEC 60529 means the enclosure is dust-tight and withstands water jets from any direction. It is not designed to be submerged – that requires IP67 or IP68.
Can you help with EMC shielding?
We can design in space for a shielding plate, conductive gasket or conductive paint on the inside. The EMC testing itself is carried out by an accredited laboratory.
How many prototypes are needed before injection moulding?
Usually two to three rounds: a first fit check, a version with sealing and assembly, and a final version that is approved before the tool is ordered.