I’ve had to do something similar and I used rice (dried). It’s light, cheap, and doesn’t roll away if you drop some (like B-Bs). It comes away from the object easily (unlike powders). It packs more efficiently than B-Bs and can’t be compressed significantly.
I’m skeptical. If by “fluffy powder” you’re referring to ground pepper, I don’t know why they would use that instead of whole peppercorns, which wouldn’t be compressible and are similar to lead shot in terms of being of relatively uniform size.
Rice, sounds pretty good, easy to get for anybody and cheap to.
Could you use sawdust? I don’t know how you’re making the bows, but it sounds like you may be producing a lot of sawdust.
The problem with sawdust is that’s it’s pretty compressible.
HoneyBadgerDC: Out of curiosity, why do you need the volume of a bow?
Several years ago I developed a bow mass program on excel that will spit out the ideal mass weight of a bow based on design and draw weight. It averages things out like handle weight primarily. Some of the guys are wanting to narrow it down more to just the actual mass weight of the bow limbs working areas. I am trying to suggest a method they can use that will be fairly accurate. I honestly do fine with the handle weight just averaged out but many are looking for a bit more precision.
Mustard seeds were one traditional medium for what you were after.
Their use in the 19th century became controversial in the 20th, when Stephen Jay Gould made an argument that one of the pioneer biological anthropologist Samuel Morton, unconsciously biased his measurements of skull capacity to show Caucasian ascendancy by smooshing the mustard seed in harder into white skulls. Reanalysis of Morton’s results has complicated Gould’s interpretation.
Some very interesting answers here. It seems like small grain rice might be a good answer, with little compressability, dry, inexpensive and reusable. For even smaller grains, you could buy washed, dry sand. I believe swimming pool filter sand might be good, as it is large grained and doesn’t stick together. It would be much heavier than rice, though, and also harder to handle and clean up. Number 8 lead shot is pretty small, but would be even heavier.
You could also try three or four of the methods listed here, and see if there are any obvious outliers among the measurements.
That is a good point
Maybe start off with water because we know that will be accurate and then base everything else on the results gotten with water. Seeds of some kind might be the best alternative but may not be easy to get or economically feasible for the guy who just tests out a few bows a year for curiosity sake. Rice, corn, beans, peas things like that are pretty cheap. Mustard might be expensive.
Grass seed is dirt cheap and is much smaller than rice.
That’s true, never crossed my mind