Word of advice
Good job. I have never made slim because of the tenon involved.
Keep the first pen. After you get a few pens under your belt go back and look at it. You will see everything you did wrong, what you should have have done, and most importantly how much you have improved.
You should also keep your first pen because out of all the other pens you make, this will be the one that gave you the biggest sense of accomplishment.