When it comes to eliminating ink mistakes on paper, correction fluid pens are a nice improvement to an already convenient product. Compared with a conventional correction fluid brush, a convenient pen tip allows you to apply white coverup in a fraction of the time. If you like correction pens but don't appreciate the fact that they tend to give you less fluid for your money, make your own using an old ink marker and bottled correction fluid.
Disassemble the pen. Remove the ink core and the tip, leaving the plastic tube empty. If the felt parts stick, grip and pull them loose using a pair of needle-nosed pliers.
Wash the hollowed pen tube in soap and water to remove any traces of ink. Let it dry. (Don't worry about permanent ink sticking to the sides of the tube; it won't interfere with the correction fluid).
Create a new sponge tip for the pen. Use scissors to cut off a section of sponge. Trim it until you can just squeeze it tightly into the tip of the pen. Ideally, it should be a tight fit, with the sponge section sitting securely inside the tip of the pen and not slipping out unless pulled; use pliers to twist and maneuver the sponge to get the tightest fit. Trim the exposed portion of the sponge into a pen tip of the desired shape and size.
Fill the plastic tube with correction fluid. Remove the tip or rear plunger (depending on how the pen is made), and pour correction fluid into the empty chamber. Fill it almost all the way, or use as much fluid as you have.
Add a small glass or metal bead or ball bearing to the chamber full of fluid, and close up the pen. This piece will mix the fluid when the pen is shaken.
Store the pen with the tip side up and the cap securely in place. The sponge tip will drip if it is stored upside-down.