Check out plastic lumber post tops and posts that you can buy, or use this page to get ideas for building your own post from scratch.

 

Instructions to build a permanent post, by John Pickle.

link to build instructions

Instructions to build a mobile post top, by Paul Alaback.

link to build instructions

Instructions to build a mobile post platform, by Vladimir Sanchez.

link to build instructions

Do It Yourself Template

post top diagram

Do It Yourself Template
A post top with multiple picture angles

post top diagram