Mike, I have been reading the discussion on redesigning the CEB press. I can't comment so I decided to just write to you.
To get reproducible dimensions AND pressure for CEB, you must have reproducible composition and mass of earth in each block. Composition can be handled by premixing large batches with the tractor and soil pulverizer. Automatic pre-weighing earth for each block seems insurmountable but reproducible weight might be achieved by a different approach: Make a preliminary compression of soil in the chamber to a preset value like 500 or 1,000 psi. This brick will have uniform width, length, and density but random height. Then "scalp" the excess off the top of this brick with a guillotine to achieve a predetermined height. Finally complete the compression to, say 2,000 or 3,000 psi or to a preset finished height. The dimensions and densities of all bricks should then be very nearly identical.