This is probably a far too specific problem, but it has been seriously nagging at me for a while.
For the better part of the past year, I've been filling 10cm x 5cm x 5cm plastic containers (yuck) with potting soil (actually cocco coir with some non-peat potting soil at about 20%)
Unfortunately, I'm sort of stuck with this non-standard container and I need to fill them "half way", which means anywhere from 77 to 85 grams. Any less or more means the final product is a little compromised. It's a little difficult because volume and weight don't always correspond and the difference of 5-10 grams might not be noticeable, but hitting 80 grams is like an obsession of mine.
For most of my time doing this, I laid out the containers on a table and eyeball filled them, getting more and more precise as things proceeded. Then I weighed them. Total time for filling, 15 minutes. Total time for weighing: 5 minutes. So the whole manual process takes 20 minutes. For 100 containers.
I recently felt the need to be able to do more in less time, so I'm currently at the end of a 3 week long quest for a prototype that would do just that.
After 3 different prototypes, the total time is still about 20 minutes. I compare it to a tandem bicycle, you just can't go any faster. There seems to be some physical limit to filling manually. One prototype seems to limit physical exertion, so I've been using that exclusively, even if the time is the same.
So, one option would be to video tape myself and try and eliminate all extra movement, or I could try and find a perfect machine that would do everything for me, or I could re-engineer everything from scratch.
Most nurseries fill to the brim and they're not as precise as I'm trying to get, so they can buy a huge machine that does things for them. Anything I do needs to fit on a desk, so space is an issue.
I've recently found that getting the soil to a fine grain without any chunks in it does help in noticing a difference in volume/weight. It does add work since I now need to sift the stuff (dreaming of a small, motorized trommel screen).
If anyone has any ideas, thanks. This is quite the pseudo-MIT project.
I can add pics of previous prototypes. Coming soon.