Need help mounting a cooling fan

I have a 4 to 4 1/2" variable speed fan, similar to the Coralvue smart 4" fan. I have it attached to a piece of egg crate. In the summer months I set the fan, mounted to the egg crate, such that it blows air across the top of my tank (Its simply set at a bit of an angle on top of the screen top - attached to nothing). Works well for keeping the tank at a constant temperature. Problem is that it is precariously mounted. If I happen to forget about it, and go to move my screen top w/o first moving the fan...... you can see the problem - it usually falls to the floor behind the tank (luckily it has never fallen in the tank). I really need a better way to mount it. Help?????? How can I do this??????

 

Mind posting a picture? Would give a better idea of the set up. Initial thought would be to mount to acrylic from Menards and clamp it to the top of the tank.

 

Have you tried using it to cool in the sump? Bungiee cord it to the light (leg)? Mount it on the wall (put it in a pic frame...use a plant hanger? Glue a magnet on it to attach to the light? Just brainstorming! lol

 

Here's a pic of the fan - attached to a piece of egg crate. Then the fan & egg crate are set/balanced between the lip of the tank and the screen top - 2nd pic. An accident waiting to happen.......