I noticed some bulrushes when I was out by the lake today, and remembered reading that you can make dip pens out of them. I grabbed one to bring home, and gave it a shot. It is a bit of a finicky writer, but pretty good results for a first try!
Step 1: Get a Sturdy Reed
You only need about 8 inches, but you will probably want a whole stick so you have plenty of chances to mess up.
I could not get my cat to leave this long, thin stick alone :D
Step 2: Cut to Length and Soak for 15 Minutes
Soak the end that will become the nib in water for at least 15 minutes, so that it will cut smoothly and not splinter.
I tried it first without soaking and it just blew to bits. You have to soak it.
It floats, so you probably have to pin it down with something.
Step 3: Create the Initial Bevel and Hollow
Make it come to a flat before the end, because you will be cutting off the end to make the square nib.
Step 4: Hollow the Reed
Step 5: Create the Side Bevel to Shape the Nib
Note the flat piece on the end. Make sure that you have a flat projection so that you can cut it square to form the tip.
Step 6: Cut the Tip Square
Step 7: Split the Tip
Rather than a cut, you want the tip to actually split, like a log hit with an axe - but you only want it to split back to the end of the nib, not split your pen in half!
Step 8: Shave the Tip to a Fine Edge
You won't be getting hair-thin lines with this pen, but you should still try to shave it as thin as you can.
Shave the rounded outside of the nib down until it is flat. Also, try to shave the inside thin too, but be careful.
Step 9: The Finished Nib
You can try to scrape some extra junk out of the inside as it gets drier, to make it look nicer.
Step 10: Ink the Nib - Do Not Dip
You should ink it from the back side only using some kind of applicator.
Here I am using an eyedropper out of a bottle of cheap india ink. Ink up the cavity with lots of ink, but don't go overboard.
Step 11: Writing!
As it has no real reservoir, this pen needs to be inked after every 1 or 2 letters. It's definitely not a daily writing pen, but it sure lays on the ink if you want to make a poster or something.
Here I just scribbled something so you can see how the pen performs.
I tried some blackletter (aka "old english/german/gothic") too, but I need more practice with blackletter writing before I show it to anyone :P