Straight from the blog, too, from C to Forth:

   : sier cr 32 0 do 32 0 do i j and if ."   " else ." * " then loop cr loop ;
   sier

Output from eforth/subleq (with do...loop set in the config):

    * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
    *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   
    * *     * *     * *     * *     * *     * *     * *     * *     
    *       *       *       *       *       *       *       *       
    * * * *         * * * *         * * * *         * * * *         
    *   *           *   *           *   *           *   *           
    * *             * *             * *             * *             
    *               *               *               *               
    * * * * * * * *                 * * * * * * * *                 
    *   *   *   *                   *   *   *   *                   
    * *     * *                     * *     * *                     
    *       *                       *       *                       
    * * * *                         * * * *                         
    *   *                           *   *                           
    * *                             * *                             
    *                               *                               
    * * * * * * * * * * * * * * * *                                 
    *   *   *   *   *   *   *   *                                   
    * *     * *     * *     * *                                     
    *       *       *       *                                       
    * * * *         * * * *                                         
    *   *           *   *                                           
    * *             * *                                             
    *               *                                               
    * * * * * * * *                                                 
    *   *   *   *                                                   
    * *     * *                                                     
    *       *                                                       
    * * * *                                                         
    *   *                                                           
    * *                                                             
    *                                                               
     ok
     ok