Looks like your doing pretty good for a beginner. A piece of marble will really be a great improvement as you will find out when you get one. I use an old tombstone that I picked up at an undertakers tombstone scrap pile. It works great but it is a bear to move. I had a friend that worked in a wielding shop make me a table on wheels for it which makes it easier to move when I need to.
Keep up the good work and keep showing your things, I enjoy seeing them.