Add a simple function in your functions.php file.
function get_button_styles(){
return array(
'button' => 'Button',
'button_red' => 'Button Red',
'button_yellow' => 'Button Yellow',
);
}
Use it to get button styles in different metabox fields
array(
'id' => 'all_btns',
'name' => 'Button Select',
'type' => 'select',
'options' => get_button_styles(),
'callback' => 'metabox_clone_options',
),