Hmmmmm. Now you have me thinking DIY diffusers. Ha.
What if you took a foot long piece of PVC, cap the ends, drill a bunch of holes in it and cover it with a couple of these boom mic covers (for lots of bubbles, haha).
http://ecx.images-amazon.com/images/I/51hoPT2AJuL._SL1001_.jpgThen just attached the pvc pipe with a conduit clip to a box filled with concrete or whatever just big enough to sink it.