Hi Soumitra, I am impressed that you are able to make pens without a lathe. I have been enjoying watching your progress and wondering how you are able to improve so much without an experienced teacher in person. My compliments!
There are a couple of things that may improve the appearance of your acrylic pens. With a blank that is so transparent, I usually paint the inside of the blank, then let the paint dry, and then glue the tube in. That will hide the silver and brass materials. Sometimes I let the materials show through the blank, but most of the time, I hide them.
Acrylics show sanding marks more than wood does, so sanding to a higher level, with finer grits, will make the blanks shine more.
Thank you for sharing your progress.