How to judge 3D print quality: a checklist for the photos and the piece in hand

You can judge 3D print quality by five signs: even, fine layers; a surface with no stray hairs or blobs; a flat base whose corners don't lift; solid walls with no gaps; and sharp letters and details. Every piece printed from filament shows fine lines between layers up close, and that's normal, not a fault.

1. Layer lines

A printer builds the piece layer on layer, usually a tenth to three tenths of a millimetre thick. The thinner the layer, the smoother the surface and the longer the print.
- Good: fine, even lines running neatly around the piece.
- Poor: wide, uneven lines, a ripple repeating next to edges like an echo of the shape, or a layer shifted off the one below.

2. Stray hairs and blobs

• Stringing: thin, cobweb-like threads between two parts of the piece. A few pull off easily; lots of them mean wrong settings.
• Blobs and zits: small raised dots on the surface, often where each layer starts. On a good piece they're hidden in a corner or on the back.

3. The base and warping

Put the piece on a flat table. If its corners lift or it rocks, it warped during printing when the plastic cooled too fast. On coasters this matters: a good coaster sits flat and the cup stays steady on it.

4. Gaps and wall strength

• Look at the top surface: it should be closed, with no missing lines or holes showing the pattern underneath.
• Squeeze the piece gently: a good one feels solid and doesn't creak. Very thin walls or an empty inside make it bend or snap quickly.
• The keychain loop in particular should be thick enough and firmly joined to the piece, since it carries the weight every day.

5. Colour

• A single colour should be even across the whole piece, with no faded patches.
• On multi-colour pieces, the borders between colours are clean, with no colour bleeding into another.
• The shade can differ slightly from the photo or between material batches, which Kun's returns policy treats as normal.

6. Support marks

Parts that hang in the air need temporary supports while printing, removed afterwards. On a good piece their spots are clean or sanded, mostly on a side you don't see. A rough, obvious mark on the front is a sign of rushing.

7. Letters and names

This matters most on pieces with a name:
- Letter edges are sharp, not melted or rounded.
- Small closed letters (in Arabic «ه», «ة», «ص»; in English e, a, o) have visible openings, not filled in.
- Every dot of Arabic letters is there and in the right place: dots are the first thing lost when a print is poor or the font is too small.
- Raised or coloured letters read from a normal distance without leaning in.

In Kun's designers, like Design Your Name Tag Keychain and the Letter Keychain With Your Name, you see the name in 3D before you order, so you can try another font if the dots or openings look too small.

8. Clickers and moving parts

• Clickers: every key presses with the same feel, gives a clear click and springs back, none stuck or tilted, and the letters on the keys are readable.
• Articulated (flexi) animals: the joints move freely from the first time without needing to be broken loose, and none is fused.

Before you buy: reading product photos

• Tell a real photo from a preview: a 3D preview shows the piece's shape and colours; a real photo shows the surface and the layer lines. Both are useful, but each tells you something different.
• Zoom in on edges and small letters.
• Check whether the seller states the material and the size.
• Remember that lighting and your phone screen shift colours a little.

Checklist when the piece arrives

• Even layers, no ripples and no shifted layer.
• No hairs or raised dots on the front.
• The base sits flat on the table.
• The top surface is closed and the walls feel solid.
• Letters are sharp, dots are there and small openings are open.
• Keys and joints move as they should.
• The piece matches your order: the name, the colours and the options.

If you find a problem

If your piece arrives broken, faulty or different from your order, contact us quickly with photos of the problem; details are in the FAQ. Fine lines between layers and small differences in colour shade or size are the nature of 3D printing and don't count as faults. To see how we watch for these points while printing, read How Kun prints your pieces.