What are micro features in 3D printing?

Tiny slots, around 0.2 mm wide, cut into a model on purpose. The slicer draws walls along each slot, so the area around them prints as solid walls instead of infill. Slant 3D uses them to make pins effectively solid.

How do you make part of a 3D print solid?

Either add a slicer modifier for that region, or cut micro-feature slots into it in CAD. The slots force walls there, so the region prints solid on any slicer without extra settings.

Is 100% infill stronger than more walls?

For a small feature, packing it with walls is the stronger and more predictable way to make it solid. Micro-feature slots do that in just the spot you need, without making the whole part solid.

3D Printing3D Modeling / DFMMicro-feature slots

How do you make one part of a 3D print solid without 100% infill?

The pin is the only part that takes a beating, but the slicer gives it the same 15% infill as the rest of the block. The fix is what Slant 3D calls micro features in 3D printing: tiny 0.2 mm slots cut into the model, which the slicer turns into walls. That pin prints effectively solid while the rest stays light.

⚡ Rule of thumb

Cut 0.2 mm slots into the region you want solid; the slicer draws walls along each slot, so that area prints as packed walls instead of infill.

Starting point

0.2 mm wide slots, cut into the region and down into the part below it

Measured

Slot width in the model

Confidence

Creator technique

▶ Source video — Design Unbreakable Pins with Perfect Tolerances — Slant 3Dwatch on YouTube ↗

Applies to

Process: FDM / filament
Features: Pins, bosses, clips, tabs, anywhere one small area needs to be solid
Goal: Local strength without slicer modifiers or 100% infill

Why it matters

Slicers put perimeters on every surface in the model. A slot is a surface. So a slot 0.2 mm wide gets a wall laid down on both sides of it.

Stack a few of those inside a pin and the walls meet each other. No room is left for infill. The pin is effectively solid plastic.

Walls carry load far better than infill, and they put material right at the outer edge where a crack wants to start.

The best part: it’s in the model. A print farm, a friend, or a different slicer all get the same solid pin, with no modifier mesh to forget.

What good looks like

The slicer preview shows only walls inside the feature, no infill pattern
Slots run past the feature and down into the part a little, so the root is solid too
The rest of the part still prints with normal infill
The outer face of the feature carries as much edge material as possible

How to apply it

Pick the small area that needs to be solid. A pin, a boss, a clip.
Cut 0.2 mm slots into it. Slant 3D uses a cross of slots inside a round pin.
Run the slots down past the feature and into the body a little, so the base of the pin is solid too.
For maximum edge strength, wrinkle the pin’s outer edge (a wavy outline) so more wall sits where the crack would start.
Slice and check the preview. Every slot should show walls on both sides and no infill between them.
If infill still shows between slots, add slots or move them closer together.

Test it on your setup

Slice the part and step through the layers inside the feature. Walls only, no infill. That’s the pass.
Print one pin with slots and one without. Snap both sideways and compare where and how they break.

Exceptions & tradeoffs

Mind you, slots this thin are close to what CAD export and slicers treat as a defect. Some will merge or ignore them. Always check the slice, not just the model.

On a big region this burns time and plastic like 100% infill would. Use it on small, high-stress features.

The 0.2 mm number is Slant 3D’s for their setup. A very different nozzle or line width may need the slot spacing adjusted, which the slicer preview will show you.

Common mistakes

Cranking infill to 100% for the whole part to save one pinSlot just the pin and leave the rest on normal infill
Stopping the slots at the base of the featureDrive them down into the body so the root is solid
Trusting the CAD model without slicing itCheck the preview; thin slots can vanish on export

Frequently asked questions

What are micro features in 3D printing?Tiny slots, around 0.2 mm wide, cut into a model on purpose. The slicer draws walls along each slot, so the area around them prints as solid walls instead of infill. Slant 3D uses them to make pins effectively solid.
How do you make part of a 3D print solid?Either add a slicer modifier for that region, or cut micro-feature slots into it in CAD. The slots force walls there, so the region prints solid on any slicer without extra settings.
Is 100% infill stronger than more walls?For a small feature, packing it with walls is the stronger and more predictable way to make it solid. Micro-feature slots do that in just the spot you need, without making the whole part solid.

Slant 3DSource & visual reference

A wrinkled outer edge to put more material where cracks start — Design Unbreakable Pins with Perfect Tolerances ↗ at 05:00.