I use baby medicine droppers, 1ml increments to 5 ml, just like a large eye dropper. Find them in the grocery store or maybe a Dollar store.
I store my solutions in glass vitamin jars, I keep the dry materials double bagged in a box under the sink, with a small plastic or glass jar to store maybe 1/4 cup of dry materials so I don't have to dig too deep to make a new solution.
I've begun adding some diluted muratic acid to see if I can keep the Plantex from getting some sort of snot-like stuff in it. Seems to work.
All my solutions are remixed about every month or two so they don't sit around too long.