This gist is a sample of code that I created for a website that I have been working on recently. I brought together two other classes, extended their functionality, made some functions more flexible, and created a cohesive class that simplifies code and saves lots of time.

JRC_Post_Type.class.php

<?php

// require the JW_Post_Type class
require_once('inc/Easy-WordPress-Custom-Post-Types/jw_custom_posts.php');
// require CMB_Meta_Boxes
require_once('inc/Custom-Metaboxes-and-Fields-for-WordPress/init.php');

/**
 * This class brings together Easy Wordpress Custom Post Types, Custom Metaboxes
 * and Fields for Wordpress, and some other functions to make custom post type
 * creation insanely simple.  This class saves hundreds of lines of code and 
 * simplifies post type creation, yet has the flexibility to allow customization
 * for more complex integration.
 * 
 * @version 1.0
 * @author  Joshua Cook
 */
class JRC_Post_Type extends JW_Post_Type
{
    protected $_columns; 
    protected $_column_functions; // the user functions to call to output column contents
    protected $_column_filters_added; // whether the column filters have been added or not

    /**
     * Sets default values, registers the passed post type, and
     * listens for when the post is saved.
     *
     * @param string $label The label for the post type.
     * @param string $plural_label The plural label for the post type
     * @param string $slug The "slug" for the post type.
     * @param array @post_type_args Override the options.
     */
    function __construct($label, $plural_label, $slug, $post_type_args = array())
    {
        if (!isset($_SESSION["taxonomy_data"])) {
            $_SESSION['taxonomy_data'] = array();
        }

        $this->post_type_label = $label;
        $this->post_type_label_plural = $plural_label;
        $this->post_type_name = strtolower($slug);
        $this->post_type_args = (array)$post_type_args;

        // First step, register that new post type
        $this->init(array(&$this, "register_post_type"));
        $this->save_post();
    }


    /**
     * Registers a new post type in the WP db.
     */
    function register_post_type()
    {
        $n = $this->post_type_label;
        $n_plural = $this->post_type_label_plural;

        $args = array(
            "label" => $n_plural,
            'singular_name' => $n,
            'labels' => array(
                'name' => $n,
                'singular_name' => $n_plural,
                'add_new' => "Add New $n",
                'add_new_item' => "Add New $n",
                'edit_item' => "Edit $n",
                'new_item' => "New $n",
                'view item' => "View $n",
                'search_items' => "Search $n_plural",
                'parent_item_colon' => "Parent"
            ),
            "public" => true,
            "publicly_queryable" => true,
            "query_var" => true,
            #"menu_icon" => get_stylesheet_directory_uri() . "/article16.png",
            "rewrite" => true,
            "capability_type" => "post",
            "hierarchical" => false,
            "menu_position" => null,
            "supports" => array("title", "editor", "thumbnail"),
            'has_archive' => true
        );

        // Take user provided options, and override the defaults.
        $args = array_merge($args, $this->post_type_args);

        // register the post type
        register_post_type($this->post_type_name, $args);
    }
    
    /**
     * Adds a new meta box to the post type. 
     * 
     * This function uses 'Custom Metaboxes and Fields for WordPress'. To
     * find out how to input fields, check the documentation for this class
     * at https://github.com/jaredatch/Custom-Metaboxes-and-Fields-for-WordPress
     * 
     * @param string $title The title of the metabox
     * @param array $fields The fields array, following the syntax of CMB
     * @param array $options Override any default options
     */
    function add_meta_box($title, array $fields, array $options = array()) 
    {
        
        $defaults_array = array(
            'id'        => str_replace(' ', '_', strtolower($title)),
            'title'     => $title,
            'pages'     => array($this->post_type_name),
            'context'   => 'normal',
            'priority'  => 'high',
            'show_names' => true, 
            #'show_on'  => array( 'key' => 'id', 'value' => array( 2, ), ), // Specific post IDs to display this metabox,
            'fields'    => $fields
        );
        
        $this->meta_boxes[] = array_merge($defaults_array, $options);
       
        add_filter( 'cmb_meta_boxes', array($this, 'cmb_meta_boxes'));
    }
    
    /**
     * Adds the metaboxes to the filter, so they can be displayed
     * 
     * @param array $metaboxes The metaboxes already added
     * @return array $metaboxes The new metabox array
     */
    function cmb_meta_boxes(array $metaboxes)
    {
        foreach($this->meta_boxes as $meta_box) {
            $metaboxes[] = $meta_box;
        }
        
        return $metaboxes;
    }
    
    /**
     * Adds a column to the post type 
     * 
     * This function takes a name and a content function as arguements and adds a column
     * to the post type main admin screen.  The content function can accept 0 or 1 arguements,
     * and the arguement will be the id of the post for that particular column.
     * 
     * @param string $col_title Title of the column
     * @param string $content_function Name of function that outputs column content
     */
    function add_column($col_title, $content_function)
    {
        $column_slug = str_replace(' ', '_', strtolower($this->post_type_name . '_' . $col_title));
        
        $this->_columns[$column_slug] = $col_title;
        
        // add the function to a variable so it can be called
        $this->_column_functions[$column_slug] = $content_function;
        
        if(!$this->_column_filters_added) {
            add_filter("manage_edit-{$this->post_type_name}_columns", array($this, 'post_type_edit_columns'));
            add_action("manage_{$this->post_type_name}_posts_custom_column", array($this, 'post_type_column_info'), 10, 2);
            
            $this->_column_filters_added = true;
        }
    }
    
    /**
     * Adds the columns between the title and date columns
     * 
     * @param array $columns Added by WordPress.  The array of the columns
     * @return array Columns array
     */
    function post_type_edit_columns($columns)
    {   
        // add the column between the title and the date
        $new_columns = array_merge(array_slice($columns, 0, 2, true), $this->_columns, array_slice($columns, 2, 3, true));
        
        // return the columns
        return $new_columns;
    }
    
    /**
     * Adds the info for each column, which is defined by the user passed function.  This
     * will run as long as the user function uses one parameter or less.  The parameter passed
     * is the post id.
     * 
     * @param string $column Slug of the column.
     * @param int $post_id The post id for that row.
     */
    function post_type_column_info($column, $post_id)
    {       
        // if the column is in the user defined columns list
        if(array_key_exists($column, $this->_columns)) {
            
            // if the function exists
            if(is_callable($this->_column_functions["$column"])) {
                    
                // call the user function to output the column contents
                call_user_func_array($this->_column_functions["$column"], array(&$post_id));
            }
        }
    }
}

// ****** USING THE CLASS ******

// create the post type
$jrc_meet = new JRC_Post_Type('Meeting Minutes', 'Meeting Minutes', 'jrc_meet', array(
    'singular_name' => 'Meeting Minutes'
));

// set the prefix for the post meta fields
$prefix = '_jrc_meet_';

// create the array for the meta boxes
$meet_details_fields = array(
    array(
        'name' => 'Meeting Date',
        'id' => $prefix . 'date',
        'type' => 'text_date_timestamp'
    ),
    array(
        'name' => 'Meeting Time',
        'id' => $prefix . 'time',
        'type' => 'text_time'
    )
);

// add the meta box
$jrc_meet->add_meta_box('Meeting Details', $meet_details_fields);

// create a function for the column content callback
function meeting_date(&$post_id)
{
    $date = new DateTime();
    $date->setTimestamp(get_post_meta($post_id, '_jrc_meet_date', true));
    if($time = get_post_meta($post_id, '_jrc_meet_time', true)) {
        $date->modify($time);
        echo $date->format('m/d/Y @ h:ia');
    } else {
        echo $date->format('m/d/Y');
    }
    
}

// add the column, using the function name as the second argument.  
$jrc_meet->add_column('Meeting Date', 'meeting_date');