A pressure-sensitive brush

You shouldn’t need to understand bezier handles to draw something worth animating.

There’s a specific kind of confidence that comes from drawing with a real pencil: the line thickens when you press harder, thins when you ease off, and the whole gesture reads as one continuous, expressive motion. Most vector drawing tools ask you to give that up. You get precise control points instead, and a line that’s technically perfect and somehow feels like it was drawn by a ruler.

Flash artists never had to make that trade. Its pencil tool took whatever rough, natural gesture you made and turned it into a clean, fillable vector shape — no bezier handles to wrestle, no control points to place by hand. You just drew, the way you’d draw on paper, and the tool did the geometry.

Pressure-sensitive drawing: how it works

A brush that behaves this way isn’t just "line width tied to pressure" — that’s the easy part. The harder problem is the shape of the stroke itself: a brush isn’t a single point, it’s a small shape (round, or flattened like a calligraphy nib) sweeping along the path your hand takes, and the outline of everything that shape touches along the way becomes the final stroke. A perfectly round nib gives you the classic even Flash-pencil line. An angled, flattened nib gives you calligraphic variation: thick where the stroke crosses the nib’s wide axis, thin where it crosses the narrow one, the same physical logic as a broad-edge calligraphy pen, translated into a digital tool.

Formo’s brush works this way: a configurable nib — circle, ellipse, rectangle, or diamond — swept along your raw pressure-and-tilt input, with independent control over how much pressure maps to how much width. And critically, none of that raw input gets thrown away once the stroke is drawn. Change the nib size or the smoothing afterward, and the stroke regenerates from your original gesture, not from some already-flattened outline, the same relationship a parametric shape has to its parameters, applied to freehand drawing. That editability isn't a one-time undo, either. It's live. Select the stroke any time after you drew it, drag the nib size or the smoothing, and it rebuilds from the same pressure curve your hand actually made, not from a flattened outline that's forgotten how it got there.

And the relationship between brush and vector runs both ways. Flatten a stroke and it becomes a plain, static vector shape — useful once you're done touching it and just want clean geometry. Or go the other direction: draw a precise Bézier path with the pen tool, then ink it with your current brush, and it becomes a real stroke along that path: same nib, same pressure profile, fully editable, indistinguishable from something you drew freehand. Precision when you want it, freehand feel when you want that instead, on the same piece of art.

Why freehand drawing works for 2d animation

This isn’t really about saving clicks. It’s about who gets to make expressive vector art in the first place. Bezier-handle-first tools quietly select for people who think in curves and control points, which is a real, valuable skill, and also not the skill most animators actually have or want to develop. A pencil-first tool selects for people who can draw, full stop, the skill practically every animator already has, and lets the geometry stay out of the way entirely.

That’s not a small philosophical point. It’s the difference between a tool that makes you learn a new way to think before you can use it, and a tool that meets you exactly where your hand already knows how to work.

Draw like it’s paper. Get clean vectors anyway