Recently I purchased a bunch of pen refills to improve some pens I have. I
       have some 80-90s era IBM pens that just had dried up plastic stick refills
       as well as some other more modern pens I like the appearance of, but had 
       crappy refills.
       
       First I have some Chinese knock offs of nicer pens that took rollerball
       refills. Pilot G2 style refills will also fit so I put an Energel 0.5 and 
       Sarasa Dry 0.5 refill. The Sarasa Dry is impressively dark and while it 
       does dry fast, it has a very wide line for 0.5 and seems splotchy.
       
       I also bought a Pilot Multiball rollerball pen to compare to the Pilot 
       Precise. It seems okay, the 0.5mm Multiball writes scratchy compared to 
       the Precise V5. I guess it has the advantage of being able to write on 
       non-porous surfaces. I also bought a Uni Boxy 100 which is very cool looking
       pen but the refill that comes with is very poor ballpoint ink. It's not 
       very dark and has a lot of resistance. I put a 0.5mm Jetstream multipen 
       refill in it. It fit, I just had to add some scotch tape in the right 
       place as a spring stop.
 (IMG) Boxy 100
       
       Now onto the real modifications. I have this cool looking IBM Printer 
       Systems Division pen that has a cylinder with text on it and two windows 
       on the outside. Every time you click it rotates through the text. I tried 
       to put a Hi-Tech-C 0.3 blue multipen refill in it, but had issues getting 
       the spring top in the right place and accidentally popped the tip off it 
       which messed up the refill and put an air bubble in it, I might be able 
       to fix it later, but it will be a messy job. So instead I managed to get
       a Zebra JK 0.7mm ball point refill in it. I had to pop the back cap off 
       the refill so it would fit in the tube with the writing and then shim it 
       with a lollipop stick it works  but it doesn't have a nice feel to the click
 (IMG) IBM printer pen
       
       Next I had a fancy looking IBM twist pen that uses cross ball point refills
       I didn't like any of the compatible refill choices so I decided to get a
       Ohto needletip ballpoint refill that was very close to the correct length.
       I had trimmed a few mm off the back of the Ohto refill then moved the screw
       cap over from the back of the cross refill to the Ohto. After that I
       discovered the spring stop on the Ohto made it too wide to fit so I filed
       those down. Then I found that the upper part of the tip was too wide to fit
       through the front of the pen so I drill it out a bit and filed it smooth.
       It works great now and I really like the Ohto needle ballpoint. The lines
       are very precise and it lets me write smaller than the Hi-Tech-C 0.4mm even
       with it being 0.5mm. Will certainly always want to have a pen with this
       refill around.
 (IMG) IBM twist pen
       
       The final of the IBM pens is this one from a charity drive in 1990. I find
       the triangle shape to be very comfortable in the hand and I like the yellow
       and blue colors. I decided to put a 0.4mm Hi-Tech-C multipen refill in black
       in it. The spring stop on the new refill was in the right spot, the refill 
       just needed to be longer. So I cut a piece of dried up stick refill I had 
       laying around to be the correct length as a spacer. I found when I worked 
       the clicker the refill and the spacer didn't always align so I joined them 
       with scotch tape. Works perfect now. Despite liking using the full size 
       Hi-Tech-C pens for diagrams I am disappointed with this vs the Ohto 
       needlepoint. Despite being a smaller tip, the line is larger and I can't
       write  as small. I also do have be careful not to touch the ink after 
       writing or it  will smudge. All this makes sense as it is gel. I prefer the 
       Ohto although it doesn't  come in colors. The Hi-Tech-C is cheaper than the 
       Ohtos but given Ohto is ballpoint it may last long enough vs this gel
       refill to be worth the extra expense. 
 (IMG) IBM Charity Pen
       
       Last but not least, I decided to change the ink in the two Zebra G-402s I
       have. I think these pens look great, but I regret getting the G vs the F
       series. The gel refills are splotchy and easy to smudge. And I've read they
       don't last long because of their size. I decided to replace these with 
       a black and blue Acroball 0.5mm multipen refills. I have tried 1.0mm Acro
       before and thought it dried too slow, but I do like it in 0.5mm. It is
       ALMOST as smooth as Jetstream. To get them to fit, I had to cut about 3-4mm
       off the back and use scotch tape as a spring stop. 
 (IMG) Zebra G-402s with Acro refills
       
       Finally here is a photo of a writing sample with all the "new" pens:
 (IMG) Writing Sample