ummm... it's not too weird but it is very different. you have to hold it kind of low on the pen. i actually had to extend the lower barrel to make the tee look correctly scaled but the ball does feel different, not as bad as you might think though. turned out a lot better that i thought it would have. (it's my first "look-a-like" pen)
remember when drilling the ball drill only 1.5" in or it will drill through the ball.(which is only 1.62" tall) and you will need to trim the bottom of the top tube a little. (trim it to fit) have fun and it is just one big guess and check process!!
and if you do make one be sure to post a picture of it on this thread!!!
The overall length of a slimline from top of nib to top of refill is 3.8". You COULD use 7mm tubing to make the "tee" up to 2.5 inches long, if you wanted to. Then, you would not have to drill as deep and the pen might be easier to use to write.