Anyone have suggestions of tools to quickly create spacers like these using 3/4"+ MDF?

Plastic 6x9 Spacers

The outer square shape is no problem, but I don't have a jigsaw for the inner cut out. Of course I can go buy one if you guys think it would be able to do the curves of the 6x9 just fine, or would a dremel rotary type tool be better? Suggestions?

I need a raise of at least 2.5" for the 6x9s from the deck, and I don't think those plastic ones would do much for the sound.

 

jig saw... you can cheap ones from like wal-mart for $20 its the easiest way to do that. and then you'll have one for if you build sub boxes and the like