Designing a multi-part 3D-printed object
Updated 5 November 2026 · 4 min read
In short
You split an object into parts when it's bigger than the machine, when part of it has to be flexible or a different material, or when it contains a mechanism. Each joint needs a clearance (about 0.5 mm in SLS PA12, 0.6 mm in MJF), a joining method (screws, dowels, clips, interlocks) and the standard hardware listed separately. objekto splits the object, checks for collisions and gives you an exploded view and an assembly guide, for up to 12 unique parts per object.
- Splitting isn't a flaw: it's often what makes an object manufacturable and repairable.
- Clearances depend on the material: 0.5 mm in SLS PA12, 0.6 mm in MJF, 2 mm in TPE.
- Springs, shafts, blades, tubes and magnets are bought in, and listed in the assembly guide.
- Design price depends on the number of unique parts; identical parts only count once.
Why split an object
- Size: each part has to fit in the machine (about 380 mm in MJF, 650 mm in white SLS). A chair or a walking cane always gets split.
- Material: a rigid handle and a soft grip can't be printed in the same material.
- Movement: a mechanism (hinge, crank, slide) means parts that move relative to each other.
- Repair: a worn part can be replaced on its own, without remaking the whole object.
- Price: two compact parts often cost less than one big hollow part that takes up the machine.
Joining options
| Joint | When to use it | Watch out for |
|---|---|---|
| Printed snap-fits and clips | Tool-free, lids, hatches, wheels that clip onto their axle | Great in PA12 and PETG thanks to their flex; avoid in brittle resin |
| Printed threads (screw and nut both printed) | Removable parts, caps, moderate loads | Coarse pitch and the material's clearance; no tapping |
| Printed pins and pegs | Aligning two parts, hinges, frames | Calibrated sockets; the pins are printed with the object |
| Interlocks, dovetails | Storage modules, hardware-free assembly | Respect the material's clearance |
| Bayonet or twist-lock | Lids, modular parts that come apart | A stop to lock it; generous contact areas |
| Hinge printed in place | Lids, light-duty joints | Only in materials that allow it (unsmoothed PA12, TPE) |
Clearances to respect
Clearance is the gap between two parts that have to slide or turn against each other. Too small and they fuse during printing or rub; too large and the assembly wobbles. The values below come from the workshop's rules, read live:
| Material | Min. wall | Min. detail | Min. clearance | Max. size (mm) | Properties | Price |
|---|---|---|---|---|---|---|
| PA12 white (SLS) | 0.7 mm | 0.2 mm | 0.5 mm | 650 × 550 × 350 | rigid · outdoor | $ |
| PA12 dyed black (SLS) | 0.7 mm | 0.2 mm | 0.5 mm | 320 × 230 × 180 | rigid · outdoor | $ |
| PA12 dyed colours (SLS) | 0.7 mm | 0.2 mm | 0.5 mm | 320 × 230 × 180 | rigid | $ |
| PA12 vapour smoothed (SLS) | 1.5 mm | 0.5 mm | 0.7 mm | 440 × 375 × 345 | rigid · outdoor | $$ |
| PA12 natural grey (MJF) | 0.5 mm | 0.2 mm | 0.6 mm | 380 × 380 × 284 | rigid · outdoor | $ |
| PA12 matte black (MJF) | 0.5 mm | 0.2 mm | 0.6 mm | 360 × 210 × 210 | rigid · outdoor | $ |
| PA12 black vapour smoothed (MJF) | 1.5 mm | 0.5 mm | 0.7 mm | 360 × 210 × 210 | rigid · outdoor | $$ |
| PA12 full colour (MJF) | 1 mm | 0.2 mm | 0.6 mm | 330 × 247 × 190 | rigid | $$$ |
| Flexible TPE (SLS, Shore ≈ 88A) | 0.8 mm | 0.8 mm | 2 mm | 220 × 190 × 190 | flexible · outdoor | $$$ |
| Flexible TPU 95A (FDM)rules to be confirmed | 1.6 mm | 1 mm | 0.8 mm | 250 × 250 × 250 | flexible · outdoor | $ |
| Standard resin (SLA, Somos GP Plus) | 1 mm | 0.4 mm | 0.2 mm | 790 × 790 × 590 | rigid | $$ |
| Clear resin (SLA, Watershed XC)rules to be confirmed | 1 mm | 0.4 mm | 0.2 mm | 790 × 790 × 590 | rigid | $$ |
| Black resin (SLA, Watershed Black)rules to be confirmed | 1 mm | 0.4 mm | 0.2 mm | 790 × 790 × 590 | rigid | $$ |
| Ultra-fine resin (MJP Visijet)rules to be confirmed | 1 mm | 0.1 mm | 0.2 mm | 298 × 203 × 185 | rigid | $$$ |
| Cast brass (lost wax) | 0.6 mm | 0.4 mm | 0.3 mm | 100 × 89 × 89 | rigid · outdoor | $$$$ |
| PETG (FDM) | 0.5 mm | 0.5 mm | 0.5 mm | 300 × 300 × 300 | rigid · outdoor | $ |
| PLA (FDM) | 0.5 mm | 0.5 mm | 0.5 mm | 300 × 300 × 300 | rigid | $ |
What doesn't get printed
On objekto, everything that can be printed is printed, joints included, even if that takes a little more material. A part is bought only when printing can't do the job — a magnet, electronics, glass, a blade — and then it's a ready-to-use catalogue part, listed with a link in the assembly guide: never cut, drilled, tapped or glued.
The AI designs the object around that part (socket, diameter, clip) so it fits as sold.
Exploded view and assembly guide
For every multi-part object, objekto shows an exploded view in the 3D viewer (parts move apart along their assembly axis), a parts list with each part's material, and a step-by-step assembly guide. The guide and the renders are free (0 credits).
Part count and price
Design is priced by the number of unique parts: a part used several times (a stool's four identical legs) only counts once.
| Size | Unique parts | Credits |
|---|---|---|
| S | 1 part | 950 credits |
| M | 2–4 parts | 1,900 credits |
| L | 5–8 parts | 3,400 credits |
| XL | 9–12 parts | 5,200 credits |
The maximum number of unique parts depends on your plan: 4 without a subscription, 8 on Creator, 12 on Pro, 12 on Studio. Printing is paid per part, in US dollars.
Frequently asked questions
What's the maximum number of parts?
Up to 12 unique parts per object on Pro and Studio, 4 without a subscription. Beyond that, split the object into sub-assemblies.
Do identical parts count?
No: the design price counts unique parts. Repeated parts are simply ordered in several copies when you print.
Can a hinge be printed in one go?
Yes in unsmoothed PA12 and TPE, with the material's clearance. Not in resin or vapour-smoothed PA12: there the hinge is printed as two parts.
Do I need screws or glue?
No: objekto prints the joints (clips, printed threads, pins). The rare part that can't be printed, such as a magnet, is listed with a link, ready to use as sold.