I make black powder, It's not very hard.
Here's what you need
You need a ball mill $42 at horrible freight and you could get a fistful of dollars off with the 20% coupon (pun intended)
Get a black powder kit from hobby chemical supply
Window screen. They say to get 16 mesh (16 holes per linear inch) I think that's what mine is, I fold it over 3 times when i use it, I'll explain more about that later in the post.
for the media in the ball mill I use round balls, dont use steel balls or anything like that because it'll spark
A gram scale, they sell cheap ones, they probably arent that accurate. I have a 20 year old one that has a price tag on the box still and it was $90 at the time
Water. That's the hardest ingredient to find
The standard ratio of ingredients is 75% Potasium nitrate 15% Charcoal 10% Sulfur. You measure out the ingredients in grams. You could simply make a batch that is 75 grams potassium nitrate (Kno3) 15 grams charcoal 10 grams sulfur. I double that and make a batch that is 150 grams Kno3, 30 grams charcoal, 20 Sulfur. pour that in the ball mill with your round balls, and let it run for 8 hours (or more). One more ingredient you need is dextrin. This acts as your binder, which I'll talk more about in a minute. after the ingredients have been mixing for the 8 or more hours, put 5% dextrin in the ball mill. Which in the 100 gram batch will be 5 grams. put in the tumbler for 20-25 minutes, not to long because it'll damage the powder. After that you have meal black powder. Pour on a out the powder over a screen over a tray to remove the round balls.
The next step is to wet the powder. Get your self some trays, your going to need 2, and a spray bottle and squirt water on the powder lightly and mix it with a putty knife or anything like that. once the powder starts to clump up in your hand, your are done wetting the powder. Make your self a sifter, and staple the window screen to it. I have folded it over a few times so you can get powder grains that are the right size. You dont want to make FFFFG powder now, as that can give you dangerous results if used in the wrong guns. Now grab a handful of powder, clump it in your hand and rub it on the screen and it will sift into the tray below (Put newspaper on the tray so it can soak up the moisture). If you make the powder to wet (which I have done numerous times) the powder sticks in the screen. Keep repeating this process till your done. now bring the powder somewhere that's dry (in the house) and let it dry for about a day. What happens to me is that it cakes up when dry, but is very easy to break apart. When it's dry take a tablespoon and pour a line of powder on a block. Now light it, be careful and see how it burns.
This powder is very light compared to store bought, (say goex) so you need to measure your charges by weight rather than volume like you do in a powder measure.
This is the first method, I'll tell you the second method in another thread.
You may think for a few dollars more (haha) you can buy a can of powder, but this actully saves you a lot of money in the long run if you do a decent amount of shooting
Phew! I hope this helps, sorry for going on so long but there is a lot of steps that need mentioning. Ask me any questions you may have!