4 steps

1. STEP 1 · DRAW THE PLATE, DO NOT PAINT ITTake the Pen (P) and draw a loop over the piece you want to mask · click to place anchors, ⏎ or a double-click closes it. Press Mask on the bar that appears. The plate is cut from your loop, and the loop itself is kept: what is on the layer is the drawing, and the pixels are only its picture this minute.
2. STEP 2 · COME BACK TO THE GRIPSRight-click the piece → ▓ Mask · edit its grips. The very anchors you placed are live again, curves and all · not a trace of the pixels. Drag one, click the path to add another, ⌥click removes one, then press Mask to lay it back. Paint on the plate with the brush instead and the grips are spent for good, because pixels say things a loop cannot · the studio tells you once when that happens.
3. STEP 3 · AND A PLATE CAN BE A FADERight-click → ▓ Mask · fade across, or fade around. Two hollow marks appear on the sheet: take the Move tool and drag either one. The first mark is where the piece is hidden, the second where it is whole. It is a FINISH · the loop underneath is untouched and ▓ Mask · no fade returns it exactly. Because it is a finish, the reel can drive it: put the record light on and drag a mark, and a fade sweeping across the picture is written down like any other move.
4. STEP 4 · A TORN EDGE, A PLATE THAT TRAVELS, AND A WINDOWThree more things on that same right-click. ⌇ Torn on the mask bar sends the plate’s edge wandering off its line on the studio’s own noise, with a faint lighter fringe just inside the rim · another finish, so pressing it again gives the clean edge straight back. ▓ Mask · copy takes the whole plate and ▓ Mask · paste lays it on any other piece, fitted to that piece’s own size (⌥ the row to replace a plate already standing there), and ▓ Mask · from the layer above cuts this plate from the piece over it, by its ink or by its light. And ⚲ The plate stays on the sheet holds the plate still while the PIECE moves, so the picture slides behind it · which is what a window is.

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