bonding FG to MDF, resin or glue?

How would you get the bubbles out???

Sorry!  I'm learning as I go along.  I new to fiberglassing also.

This is what 97blackrodeo is trying to say, and myself also.  Put the fiberglass piece up to the MDF that you want to bond to.  Mark outside line with a sharpie (marker).  Cut or tear some matting to put around the mark and resin the crap out of it.  Immediatley put the fiberglass piece to the MDF before the resin dry's.  Then you can add some layers to the ridge from the MDF to the fiberglass.  To get the bubbles out just keep adding resin and pat the cloth with your brush.  You don't want to brush the resin on, you want to blot, or pat it on to penetrate the material. 

On a side note, I don't see why you can't bond the MDF to the fiberglass with liquid nails, as  you said at the first of the post.  I would also resin the outside or inside of the box for added structural integrity.  You could run a thick bead around the lip of the fiberglass piece and attach it to the MDF.  Be sure to let it dry overnight, and be sure to add some matting around the area that you bonded to.