Rrr!

I just ordered a sub and enclosure. It is an 8" ground shaker box and an Infinity Refence 8" sub... but the sub doesn't quite fit in the box. Pic related. This lets quite a bit of air through and destroys bass response.

I don't have any wood cutting tools. Is there someplace I can take it to expand the hole a little, or something I can buy cheaply to do it?