Comment by shadowgovt

Sounds doable, but again, you're comparing that approach to:

- get some string

- measure a length between your low and high points

- fold it in half

- make a mark at the halfway point of the string

- fold it in half again, etc.

No candles, projection, transparent or slotted ruler, wall, or carefully moving one's hand back and forth under projected magnification needed. Just some string.