Here's the drawing:
![Image](http://imagizer.imageshack.us/v2/800x600q90/673/3u4fQK.png)
It consists of a base screen attached to a couple of supports.
There's also a replica top screen to sit on top to allow me to close off the openings a little if needed.
Here's a view of the completed product from the underside (still needs a clean):
![Image](http://imagizer.imageshack.us/v2/800x600q90/538/rrECFO.jpg)
Here's a view of the top:
![Image](http://imagizer.imageshack.us/v2/800x600q90/673/ESvugS.jpg)
Fingers crossed this does the job for me.
Cheers,
Mech.