Build your own product: Pick X products and we'll put that in a box.
<fieldset>
<legend>Your pack product</legend>
<table style="clear:both">
<tr>
<td><label for="pack_quantity">How many items in the pack?</label></td>
<td>
<select id="pack_quantity" name="pack_quantity">
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6" selected="selected">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
<option value="11">11</option>
<option value="12">12</option>
<option value="13">13</option>
</select>
</td>
</tr>
<tr>
<td><label for="pack_favors">Enter your comma-separated list of favors:</label></td>
<td><textarea rows="4" cols="50" id="pack_favors" name="pack_favors" /></td>
</tr>
</table>
</fieldset>