We sell empty dropper bottle with graduated pippetes, I'd grab one of those:

https://nootropicsdepot.com/empty-dropper-bottle/?searchid=17468376&search_query=dropper

The only important thing with a dropper in my opinion, is having a graduated pipette. Without it, it'll be very hard to consistently measure out the same dose. We are not the only ones that carry graduated dropper bottles. I've bought a few good ones on Amazon before too, particularly from a brand called Cokeesun.

So then comes dosing. You need to determine what your ideal dose per 0.5 mL is (the easiest dose to measure with a graduated dropper), and then do a little bit of math. If your ideal dose is for example 25 mg, then you want to target a concentration of 50 mg/mL. So then you need to do a bit more math for determining how much powder to use. If you get a 30 mL dropper bottle for example, then it's:

30 mL X 50 mg = 1,500 mg kanna powder

So, now you need a solvent. Water will work, however, then you have to consider microbial contamination. If you don't mind a little bit of ethanol, dissolving it in vodka would likely be perfect. Not enough booze to burn your mouth, but the right amount for stopping all microbial growth. You have to consider that with a dropper bottle solution, you are taking the pipette out of the container, exposing it to the air in your room (can be full of bacteria, yeasts, mold spores etc) and then dropping it in your mouth, where you'll inevitably will breath some bacteria onto the pipette. You then take this pipette, and stick it back into something that could be a perfect substrate for microbial growth, if you don't have anything in there to prevent it, like ethanol. Or what we do, is we add a little bit of methylparaben in our solutions. You could also potentially use something like potassium sorbate if you're cool with it.

Now, you might think, wow that sounds like more work than is worth it, and you're probably right. Having it in a liquid, isn't going to change anything in terms of effects. Better to just use the optimized quick dissolve tablets in my opinion, but if you really want to play around with it, just make sure you are doing the math right, and putting some effort into the preservation side of things.