How to Use Custom Support Painting to Place Supports Precisely

Auto-generated supports are a blunt instrument. They cover overhangs you never wanted touched, miss a delicate bridge here and there, and leave scarring exactly where the eye lands first. Custom support painting hands that decision back to you, letting you brush enforce and block regions straight onto the model surface so the slicer builds material only where your part actually needs it.

Quick Answer

In PrusaSlicer or OrcaSlicer you paint enforcers (left-click) where you want supports added and blockers (right-click) where you want them removed, then run the generator. The slicer obeys your painted regions instead of guessing, which is the cleanest way to support fragile geometry without scarring visible faces.

What support painting actually does

The automatic support generator looks at overhang angle alone. Anything steeper than your threshold gets propped up, anything shallower is left bare, and it has no idea which faces you care about. Support painting layers a manual override on top of that logic. An enforcer region tells the slicer "build support here no matter what the angle says," and a blocker region tells it "never build here, even if the overhang looks risky." You are not redrawing the supports by hand, you are steering the generator with two simple brushes.

The tool only appears in Advanced or Expert mode. In PrusaSlicer it is the paint-on supports icon on the left toolbar; in OrcaSlicer it is the support painting brush. Both give you per-face control, undo on every stroke, and a live preview of where material will land before you slice.

Setting up your paint session

1. Switch the slicer to Expert mode so the painting tools are visible, then import your model and orient it the way it will print. Orientation first, always: paint follows the model, so repositioning afterwards wastes the work.
2. Set your support style to "Support on build plate only" or "Everywhere" depending on the part, then choose "Support: For support enforcers only" if you want zero automatic supports and full manual control. This is the mode that gives you a blank canvas to paint on.
3. Open the support painting tool. Adjust the brush size to suit the feature you are working on, smaller for fine detail, larger for sweeping flat overhangs.
4. Left-click and drag to paint enforcer regions onto faces that need propping. Right-click and drag to paint blocker regions onto faces you want kept clean. Hold the erase modifier to clear a region you got wrong.
5. Rotate the model as you go. The faces you cannot see are the ones that catch you out, so spin it underneath and check the true underside of every overhang.

Where painting pays off

Tall thin spires, overhanging text, and figurine chins are the classic wins. The auto-generator either floods them or skips them, and either way the surface suffers. Paint a tight enforcer only under the tip of a spire and you support the one millimetre that matters while leaving the shaft clean. Paint blockers across a gently sloping shoulder and you stop the slicer wasting filament on an overhang that would have printed fine bridged.

It also rescues prints where supports were fusing into a recess you could never reach with cutters. Block the recess, enforce a nearby ledge instead, and the part comes off the plate without a fight. A sharp pair of flush cutters and a deburring tool from the printer accessories and tools worth keeping on the bench make the cleanup that remains genuinely quick.

Reading the preview before you commit

Switch to the support preview or slice the plate and step through the layers. Enforced regions should show support structures growing under them; blocked regions should show clean air. If a painted enforcer produced nothing, your support style is likely set to a mode that ignores enforcers, or the region is too small for the support spacing to place a pillar. Widen the brush stroke or drop the support pillar spacing and re-slice. If a blocker is being ignored, check that it sits on the actual overhanging face and not the wall beside it.

Frequently Asked Questions

What is the difference between an enforcer and a blocker?

An enforcer forces supports to generate in that painted region regardless of overhang angle. A blocker prevents supports from generating there even if the geometry would normally trigger them. You use enforcers to add safety where you need it and blockers to protect surfaces you want left untouched.

Why are my painted enforcers not generating any support?

The most common cause is the support style. If supports are set to off, only the "For support enforcers only" mode will honour your enforcer paint. The other cause is a region too small for the pillar spacing to fit a support, so widen the stroke or reduce the support spacing and slice again.

Does support painting work in both PrusaSlicer and OrcaSlicer?

Yes. Both slicers offer per-face enforce and block painting with a live preview and undo on each stroke. The controls differ slightly but the workflow is the same: left-click to enforce, right-click to block, then run the generator.

Should I orient the model before or after painting?

Always orient first. Painted regions are tied to the model faces, so if you rotate the part after painting, the supports you carefully placed will end up in the wrong spot relative to the build plate. Lock in your orientation, then paint.

Can painting completely remove the need for supports?

Sometimes. On parts with mild overhangs you can block almost everything and lean on bridging and good cooling instead. On steep or tall geometry you still need targeted enforcers, but painting lets you use far fewer supports than the auto-generator would, which saves filament and cleanup time.