Shrinking down stencils and rulers to a handy bookmark format.
Keep your drawing tools exactly where you need them!
These are printed in three 0.2 layers - just enough to not bulk up a sketchbook, and easily carry more than one.
I've used the Hilbert Curve on the top surface layer. I find it produces the nicest finish (but it does almost double the printing time).
I've designed a few basic stencils - circles, squares, triangles and ellipses. Each is a separate object, so you can uncheck the ones you don't want.
If you use translucent filament, you can see your sketch through the stencil as you draw. Recommended!
The tab on the short side gives you a quick glance of what bookmark you've got between those sketchy pages:
Happy sketching!