🦋 Mirror Mirror

$ man symmetry

The left half of a figure is drawn — draw its mirror image on the RIGHT of the dashed line, in as many strokes as you like, then press done ✓. Undo ↩ removes the last stroke, clear restarts the figure — no penalty. Lifting between strokes costs nothing at all, so short marks and a mouse or trackpad are perfectly at home here.

Starting is forgiving: press up to a hand's width left of the dashed line and the stroke slides onto it. Only a press well into the left half is turned away, because that half is the figure you are copying.

The thin bar under the figure is your ink. Redrawing the same curve over and over uses it up; when it runs out the drill stops taking ink and asks you to press done ✓ — it never scores you mid-stroke. The first 20 px of every stroke are free, so marking heights costs nothing.

Scored on how far your mirrored strokes land from the true curve — measured in pixels, in a band that grows with the figure but never gets stricter than a real hand can hit, and that widens for a mouse or a finger (the corner of the HUD says which the drill graded for). A careful mirror reaches 100 on any device. The reveal marks your widest misses with short whiskers; tap it to jump ahead. Keyboard: Enter = done / next, Backspace = undo.

Studio tip: don't copy the outline line by line. Pick three or four heights, look at how far the drawn half sits from the dashed line at each one, put a short mark that far out on the right — then join your marks. Symmetry is measured, not felt.

Each figure's reveal moves on by itself after a pause — but the pause is a floor, not a clock. A quick tap jumps ahead, and a press you keep down holds the reveal for as long as your finger does.