I have to describe this... I have part of the solution:
You have a stainless or teflon small rectangular plate.
perhaps 2" long, maybe 1/4" wide or less to specs
around the thickness of a dime.

you cut out squares, one more left to center. one more right to center
you cut the holes precisely to the amount of your powder that will be dispensed
***
the actuator moves this piece back and forth over a dispensing hole
Each side is fed by square teflon tubes (or similar)
it will go under a center piece that is exactly the height over the dispensing hole
goes right, dispenses, goes left, dispenses. depending on the compression (or none) of the materials involved, compacting the material or not, your material will be perfectly dispensed.
rocker type.

 

I have and use the RCBS 1500 as well as other scales and volume dispensers.

There are a few different ways to go about doing what you want to do and keeping on the economical side. Without a scale for the time being. Powders have a Volume Measured Density. The (VMD) of a powder is the volume in cc's (cubic centimeter) that one grain of powder occupies. This can be used to calculate the dipper, disk cavity or powder measure setting required to obtain a desired weight of powder. Note I used grains and not grams as my unit of measure. I use grains because grains is the unit of measure guys rolling their own ammunition use. VMD is going to be VMD regardless of unit of measure.

If a powder has a VMD of .1064 , and the desired charge weight is 4 grains, 4 x .1064 = .4256, or . 43 cc's. Using a scale you can calculate a VMD for whatever you have for your powder.

Take a known measure. a thimble a dipper anything known. I can give you a few demo examples I use. I have a collection of dippers which I have not used in years but here is an example of some powder and a dipper.


The little yellow dipper has a volume of exactly 2.8 cc. We fill the dipper by simply scooping up powder.


I level the dipper by just running a straight edge across the top, any business card will do. I know my powder VMD and I know my volume so I can calculate what my weight will be. Incidentally while dippers are sold you can easily make your own. 1 cubic centimeter of water (cm3 - cc) = 1.00 grams of water (g wt.), note the unit of measure is grams for the water. Using simple math all of this is easy to figure out. Anyway you get the idea.

You can also use a powder scale with a trickler which some guys have automated. You take a basic balance beam scale and add to a simple powder trickler. Remove the thumbscrew cap and add a small slow motor. Set a weight on your beam scale and use a slotted optical sensor. When the sensor trips the motor stops. Guys are hitting +/- 0.1 grain easily.

There are more ways to go about this. You are not going to get full automation for under $100. My RCBS 1500 comes in a little under $400 and a good match master almost $900. Just a matter of how you want to go about it. You can make your own dippers with empty .22 cal rimfire cases of similar.

Ron