Extending Timber\Post class issues... https://github.com/timber/timber/issues/1197

MyPost.php

<?php

class MyPost extends Timber\Post
{
    public function __construct()
    {
        parent::__construct();
    }
}

single.php

<?php
use \Timber\Timber;

$context = Timber::get_context();
$post = Timber::get_post(null, 'MyPost');
Timber::render(array('single.twig'), $context);