Measuring the parameters of a mix, doesn't need to be super accurate. This is the method I used, can be done with household items First some terms, a fl oz refers to a volume measurement not weight. A fl oz is approx 30 ml.

Items used 12oz plastic Cup, 16oz measuring cup, soil mix

Fill plastic cup with water, then pour into measuring cup, note volume in oz.

Punch hole in bottom of cup, and fill with mix to the level of the previous water level.

Place finger over hole in cup, slowly add water to mix till it reaches the surface of mix.

Record water left in measuring cup.

Let cup with mix, drain into measuring cup, record water in measuring cup.

Using the data recorded you can calculate TP ,AP,WP, WHC of mix. This should give enough accuracy. You can use a metric rule to measure water height in measuring cup or other linear container ( Clear Pipe,Clear Cylinders, Jar etc) if wished also.

I was going to measure Pumice with different proportions of Peat Moss, Pro Mix HP, Oil Dri 100%, Perlite 100%., and Redwood Shavings 100%.