I made a tincture recently, using ISO oil and Bacardi 151. Unfortunately I didn't measure how much ISO oil I used. Volume-wise it could have been about 6 - 10 pea size balls (1 cm balls).
Added the ISO oil to 750 ml of Bacardi 151. I got all the oil out of the container by soaking it in the Bacardi -- it's an excellent solvent! Heated the entire bottle for about 30 minutes, not quite boiling the alcohol. Not boiling it down, just trying to cover my bases a bit in case there is something to the heating/decarboxylization/activation thing.
1 - 1.5 capfuls of this tincture keeps me happy for most of the evening. I do have a low tolerance, though...
I also see a similar settling / sediment layer at the bottom if the bottle sits still for a day. Shaking the bottle for a 5-10 seconds mixes it back up, and it seems to stay in suspension for hours and hours.
So far it's my favorite cannabis ingestion method