When a plastic component breaks and you can't find a replacement, measuring the broken part for modelling is often the best path forward. Even if the part is cracked, warped or missing sections, it's usually possible to extract enough information to produce an accurate 3D model.
What you'll need
- Digital callipers — essential. Analogue callipers will work in a pinch but digital ones are faster and easier to read accurately. A cheap set (under £20) is adequate for most purposes.
- Ruler or tape measure — for overall dimensions that exceed calliper range
- Paper and pen — sketch the part and annotate dimensions as you go
- Camera or phone — photographs from multiple angles, with a scale reference
Step 1: Photograph the part before doing anything else
Take photographs from at least 6 angles: front, back, top, bottom, left, right. Put a ruler or known-size object in frame for scale. These photos are your reference — they capture context that's easy to forget once you're deep in measurement.
If the part is in multiple pieces, lay them out together and photograph the assembly showing how they relate to each other.
Step 2: Measure overall dimensions first
Start with the biggest dimensions: overall length, width and height. These anchor everything else. Write them down immediately — it's easy to forget which number was which if you leave it.
Use the outside jaws of the callipers for external dimensions. Take each measurement at least twice and compare the readings — if they differ by more than 0.5 mm, something shifted during measurement.
Step 3: Measure all functional features
Work methodically through the features that matter for function:
- Hole diameters — use the inside jaws. Measure at multiple depths if the hole isn't fully circular.
- Hole positions — measure from a reference edge to the centre of each hole
- Wall thicknesses — use the depth probe or outside jaws on cross-sections
- Snap features and clips — measure width, thickness and undercut depth
- Groove and slot widths and depths — use the inside jaws and depth probe
- Mounting face flatness — check if the mating surface is flat or has locating features
Step 4: Dealing with broken geometry
If the part is cracked, you can often still get accurate measurements by:
- Reassembling carefully — hold the pieces together with tape or a clamp and measure as if it were whole
- Using symmetry — if the part is symmetric, measure the intact half and mirror it
- Inferring from context — if a feature engages with another part, measure the mating feature instead (usually easier to access and undamaged)
Step 5: Sketch your measurements
Don't just record a list of numbers — sketch the part (it doesn't need to be artistic) and annotate each dimension on the sketch. This way you'll know which measurement refers to which feature when you or someone else tries to model it later.
Sending measurements to us
If you'd like us to create a model from your measurements, get in touch with your annotated sketch, photographs, and a description of the application (what does the part do, what does it connect to, what loads does it need to withstand). We'll let you know if it's something we can help with and give you a cost estimate for the modelling work.
For parts where you already have a model, use our instant quote tool to get a price immediately.
Common questions
Can you copy a part that is broken in two?
Usually yes. If the break is clean and you still have both halves, the original shape is fully recoverable. Send both pieces and we rebuild the geometry.
What if a piece is missing completely?
We work from what survives plus the mounting it fits. Symmetry, screw spacing and the mating part normally pin down the missing section closely enough to fit first time.
Do I need callipers to measure it?
Callipers help, but a steel rule and a clear photo with the rule in shot gets us most of the way. We confirm critical dimensions before printing anything.
Which measurements matter most?
Anything that has to fit something else: hole centres, shaft or spigot diameters, clip spacing and overall thickness. Cosmetic curves can be approximated without affecting the fit.
Should I post you the broken part instead?
If you can spare it, yes. Having the original in hand is faster and more accurate than any set of measurements, and we post it back with the new one.
What if the replacement does not fit?
Tell us what is wrong and send a photo. If the error is ours we remodel and reprint it at no extra cost. Getting the fit right is the job.
Published 9 September 2026 · last reviewed 5 October 2026.
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