Isolate & cut.

Isolate lives on the rail right after Pick. It doesn't paint — it changes what you can see and reach, so the tools that do paint can get at a surface that another part of the model was blocking.

It works two ways. Cut chops the model along a line you drag and hides everything in front of that line, toward you. Isolate marked area keeps a patch you've marked plus everything behind it, and hides whatever's between that patch and the camera. Either way the hidden geometry doesn't just disappear from view — it also goes un-clickable, so a stroke can't accidentally land on the thing you were trying to see past. Your paint goes where you're looking.

Nothing is deleted. A Show all pill sits at the top of the viewport the moment anything is hidden — one tap restores the whole model, paint and all.

• Painting into a crevice. Between fingers, into a cockpit, behind a cape, down the throat of a dragon — anywhere a near surface keeps stealing your clicks.
• Reaching the inside of a closed form. Cut the front off a helmet or a hull and paint the interior wall like it was facing you the whole time.
• Cleaning up a back face you can't orbit to. Isolate it and the camera-side geometry stops getting in the way.
• Checking a slice of the model without committing to anything — cut, look, Show all.

Cut — slice along a line:

1. Pick Isolate on the rail, then choose Cut horizontally or Cut vertically.
2. Drag a line across the view. The model chops at that line and everything in front of it — toward you — hides.
3. Wrong side gone? Hit Flip to swap which half stays.
4. Paint the revealed surface. The hidden side is un-clickable, so every stroke lands on the geometry behind the cut.
5. Tap Show all (the pill at the top of the viewport) when you're done. The model comes back whole.

Isolate marked area — keep what you marked:

1. Mark the surface you want with the Mark tool — drag over the patch you care about.
2. Switch to Isolate and choose Isolate marked area.
3. Layerpaint keeps your marked patch and everything behind it, and hides whatever was in front — a finger over a crease just vanishes.
4. Paint freely. What's hidden can't catch your clicks.
5. Show all to bring the rest back.

• Cut, then Magic Fill. Once the front is hidden, an interior wall behaves like any other exposed surface — tap it with Magic Fill and it floods to its seams.
• Combine a cut with a mark. Cut away the bulk that's in the way, then Mark a precise patch on what's left and scope a clean-up to just it.
• Orbit while isolated. The hidden geometry stays hidden as you turn the model, so you can work a recess from a few angles without it filling back in.
• Drag, don't tap, for a cut. The cut follows the line you draw across the view — a stray click won't place it.