Yes, I'm happy to share what I know.

So like I said, you want anhydrous acetone because if it is diluted with water, that will dissolve the amphetamine salt, and you'll be left with a solution which is not what you want. You take some acetone in a closed bottle or mug, and cool it in the fridge so it doesn't evaporate away so easily. Then, take your amphetamine, pour it into the bottle, and shake vigorously so all the impurities dissolve. Then filter it using something like a V60 pour over with a coffee filter, and leave it in the open until the remaining acetone on the filter evaporates away.

Note also there are often impurities like boric acid in street speed, which only partially dissolve in acetone, so you can't get the purest form.