The original pointing figure may have come from an American drink called Moxie http://drinkmoxie.com/ The pointing hand goes back a long way in the history of publishing, Wikipedia says;
"Though rare today, this symbol was in common use between the 12th and 18th centuries in the margins of books, and was formerly included in lists of standard punctuation marks. It primarily fell out of favor because its complex design made it unfit for handwriting, and its wide size made it difficult to fit on a typewriter or on early, low-resolution, monospaced computer fonts. It was therefore not included in ASCII. It was, however, added to Unicode. Historian William Sherman speculates that as the symbols became standardized, they were no longer reflective of individuality in comparison to other writing, and this explains their diminished popularity.
Manicules are first known to appear in the 1100s in handwritten manuscripts in Spain, and became common in the 1300s and 1400s in Italy with some very elaborate with shading and artful cuffs. After the popularization of the printing press starting in the 1450s, the handwritten version continued in handwritten form as a means to annotate printed documents. Some were playful and elaborate, but others were as simple as "two squiggly strokes suggesting the barest sketch of a pointing hand" and thus quick to draw. Manicules also became a printed character, and from the 1400s to 1700 with a few exceptions (such as figurines of pointing men and women) were horizontal, small, and uniform in appearance. In the 1800s and 1900s, the pointing hand became more popular in publications, advertising, and directional signage. Some fingerposts have relief-printed or even fully three-dimensional physical manifestations of pointing hands, The United States Postal Service has also used a pointing hand as a graphical indicator for its "Return to Sender" stamp."
So as Google couldn't really help me (big difference between digital media and paper based communication....) I headed out into the real world and raided a rack in my local supermarket. There were a number of different leaflets from local attractions displayed randomly in a rotating stand with 4 faces of leaflets mostly either A5 or A4 folded in 3 though there were a number of flyers at 1/3 A4 size some and booklets that fitted into the slots.
Design was pretty variable, one seemed to be an exercise in cramming as much colour and images into one small space to attempt to make it stand out. En mass there was no single leaflet that stood out and I guess they were relying on bored shoppers (or their children) browsing them. I also found a leaflet for a local lavender farm that had been put through the door and a promotional leaflet for an art gallery which I picked up from a table at an exhibition. None of the leaflets were asking for volunteers though I have seen some pinned to notice boards in shops and the library. I guess they may be put though a door but there could be some reluctance to do this due to fears of attracting unsuitable applicants? I guess you would want to target the "right" sort of people for your task. There was fair in my local shopping centre recently with stalls looking for volunteers but it was before this task so I'm afraid I have no leaflets.
I'm sure that the lack of variety in folding is down to cost, there must be machines that can print and fold the standard designs but novel designs may have to be folded by hand and would look less professional if they weren't folded accurately. It's a shame as I'm sure they would stand out more.
I had some fun exploring different folds
First I tried a variation on the A5 size by folding the 2 edges to the middle creating a leaflet that would fit into a standard leaflet slot but which looks a little different
A variation on this would be to fold so that one flap is bigger than the other. It is logical (and maybe too predictable?) to have the title running down the smaller fold
Folding an A4 paper along the long edge creates a tall leaflet which would fit in the rack but stands taller than standard competing leaflets and therefore may grab attention better however it would need to be sufficiently strong paper to stop it from drooping.
I like the idea of oblique folds to create a triangle which points the viewer to look through the text a bit like the pointing hands employed by early printers
This lead me to further triangular folds
The problem with this is that you can see the letters V and R from the word Volunteer inside so they need to be at a better angle
which changes the inside layout
with lettering this gave me
It needs pictures of happy volunteers and some colour to make it stand out but here is a folded mock up. The lettering needs to be moved more to the left but with some images or colour the balance could change.
which opens initially to reveal the lettering
I'm not sure that this would be easy to mass produce because the folding is fiddly and needs to be accurate.