Some thinking is spatial. Grape has a drawing canvas that lives inside a note rather than in a separate file.
Adding a canvas
On desktop, type / and choose Drawing, or use the drawing button in the editor toolbar. On mobile, tap the brush button on the toolbar above the keyboard, and the canvas opens full screen for finger or stylus drawing.
The tools
One bar along the top of the canvas, the same one a handwriting note uses: hand, select, pen, highlighter, eraser, shapes, text and picture, then undo and redo at the far end. The pen has four brushes (ballpoint, fountain, brush and pencil), shapes cover rectangle, rounded rectangle, ellipse, triangle, diamond, line and arrow, and tapping the tool already in hand opens a card with its settings, its thickness and its colour. Zoom sits at the bottom left. On desktop you can pan a large drawing by holding Space and dragging, or with the hand tool.
For pages rather than a single canvas, a notebook you write on with a pencil, see Write notes by hand.
What it is for
Freehand sketching, diagrams, wireframes and marked-up pages. Drawings sync between devices, so a sketch made on the phone is waiting in the note on your desktop.
Keeping it findable
Add a line of text under the drawing describing what it shows. Search reads the text, so a one line caption is the difference between finding the sketch later and scrolling for it.