radios options separated into different wrappers
In my opinion you can achieve that with a theme function, specified like this:

$element['example'] = array(
  '#type' =&gt; 'checkboxes',
  '#title' =&gt; t('Example checkboxes'),
  '#options' =&gt; $options,
  '#theme' =&gt; array('custom_options'),
);


And then, you can write down the output just as you want here:

function theme_custom_options($element) {
  $output = '&lt;div id="blah"&gt;';
  $output .= $element['#options'][0];
  $output .= $element['#options'][1];
  $output .= '&lt;/div&gt;&lt;div id="blablah"&gt;';
  $output .= $element['#options'][2];
  $output .= $element['#options'][3];
  $output .= '&lt;/div&gt;';
  // ETC...
  return $output;
}


Does it seem correct?