To build a 3D Pentagon with CSS3, we use 5 squares, 2 trapezoids and 2 triangles. Squares are built using CSS3 Transform properties and triangles/trapezoids use both CSS3 Transform and CSS3 Border Style properties. Demo.
To build a 3D Trapezoid with CSS3, we use 3 squares, 1 rectangle and 2 trapezoids. Squares and rectangle are built using transform properties and triangles use both transform and border-style properties. Demo.
Freelance Web Developer (Frontend, Backend) based in France using open source technologies and tools since 1996. Linux, Apache, PHP, MySQL, jQuery, CSS3 and more. I am involved into eCommerce projects using Magento since march 2008 and Code Igniter since 2011.