:headbang2: Not bad at all
The foam is to alleviate some weight and pressure points and prevents scratches too. It isn't absolutely necessary with smaller projects. HD and Lowes sell white sheets of styro that is 3/4" thick that would probably work better for many people.
It's not too late for that mossy coconut...the one in the tank, not on your shoulders

. You can buy brown hair nets (usually 3 for $1 at pharmacy). Pull the cave out, sprinkle it with moss, stretch the hairnet over it and tie it off underneath. Cut a small hole where the door is (it'll stretch so start small) and you're set. Put it back in and in a few weeks it'll be grown in.
tennesseemom, I have in my sig of pics my diy corner tank hood if you're interested. One thing I would change is a single hinge at the front instead of two.