A very serviceable pen made out of a reed in about 10 minutes work.
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 need a dead bulrush or similar reed. Pull off the ragged layers until you are down to something that is firm and stiff.
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
Slice it down to about 8" long. That's a well balanced length for a pen.
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
Slice into the reed to create a tapered end. Don't try to do it in one slice, progressively carve it down.
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
Scrape out the interior flesh, leaving only the hard tube. Scrape gently, it's easy to destroy the tube.
Step 5: Create the Side Bevel to Shape the Nib
Rotating the pen to the side, carve into the sides of the nib to form the proper nib shape. If you have ever seen a fountain or dip pen, you know what shape you're going for.
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
Hold the pen against a flat surface and press down with a sharp knife to square off the end. This forms your writing edge.
Step 7: Split the Tip
Splitting the tip forms the ink channel to allow the ink to flow properly. Put the pen flat on the table and press the knife gently into the center of the tip to split it. Be careful, this could really get out of control.
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
The finer the edge, the more expressive the writing, as you can go from ultra-fine lines to hugely fat ones.
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
Here is a pic of the finished nib, ready to write.
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
It's a "dip pen" - but, DO NOT DIP IT! Dipping will overload it and blots will go everywhere.
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!
Hold the pen at a high angle to the paper. I found this gave better flow. Don't press at all, just let the ink flow - pressing will spread the tips, and leave gaps. You can see one at the start of the T.
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