20mg/ml in grain alcohol should not need any shaking. Put a bunch of peppermint extract in it and it's not too bad. Personally, I just take grain alcohol, mix things to 20-25mg/ml and then put a shot of water in a glass, suck up 1ml out of the liquid oral and squirt it in the shot of water then down it. Put tad more water in the cup, swirl it and down. You get everything. No shaking no stirring takes like 10 seconds.
For 20mg/ml you just need 1 gram of powder in a graduated cylinder or something that is marked at 50ml. Now put your powder in, add grain alcohol (everclear) up to the 50ml mark. Heat it up just below 78C (the boiling point of everclear) No it will not spontaneously combust. Make sure you have it stirring as you heat. Magnetic stir plate and proper equipment would be nice. Now let cool and that shit will NEVER have to be shaken up!