My wife is inclined to put things back in the wrong place in our IKEA kitchen. If other people have a similar problem, this might help to remind them where to replace food cupboard items.
This is a movable clip that helps to point to the correct place on a shelf. Can be written on but you could also stick a piece of wipe-on, wipe-off material on it.
However, not all shelves are the same thickness, so I would print one first to try, and then adjust to a size that is a snug, but not too tight fit. These ones are designed for 18mm shelves.
Printed on a Wnahao i3 with PLA - no support - but might be better with a more flexible filament.