Boyd I think nobody needs a bendometer!! if you know a tune very well then try playing it on your harp to get the pitch right.... nusery rhymes and hymns are great to get your bends right since most people are familar with these tunes you will know if you got the pitch right or not!! just my 2cents worth of advice.
example Old mcdonald for the 3" bend.... or three blind mice 3 3" 2
The problem with a visual aid is that you will be looking at a meter while placing your bends. This is one step removed from hearing the correct pitch in your head and is, IMO, a longer path up the mountain.
Better to have that pitch firmly in your inner ear first and then "telling" the harmonica to play it via your technique.
For instance, if you are going for that 3 hole first inhale bend (minor third), try playing 2 hole inhale, sing that note as the word "That". Get it in good pitch (you don't have to be a great vocalist either).
Now, think of that song "Spoonful". It goes "That spoon...that spoon...that spoon-ful". Most of you already have it in your memory banks so it should be real clear.
Now, play 2 hole inhale to get your first note for "That". Next, sing "That spoon...that spoon...that spoon-ful". It is merely 2 hole inhale to 3 hole first bend inhale alternating back and forth. Really sing it and nail the notes.
Finally, make the harmonica "sing it". Use your ear to pull that 3 hole first inhale bend into correct pitch.
Alternate between singing and playing until the harmonica sounds exactly like your singing. You can even pause on "Spoon" to sustain the note, really reinforcing that pitch and telling the harmonica what to do.
