Thanks to all the info in this thread i decided on the Enthoo Evolv ATX case and what to do with it.
I figured id add a few photos to show what I've done and hopefully it can help others also.
At work we have a water jet cutter (not something available to everyone but what i used).
Aluminium perforated sheet (Ebay)
Black spray paint (Plastikote)
Metal Epoxy Glue.
The drawing office kindly set this up for me to use with the water cutter. (Sizes may help others do the same)
The water jet cut out the holes
Sanded the edges lightly
Sprayed my perforated sheet black
Trial fitted it all using double sided sticky tape
Glued the perforated sheet in place.
Masked it all off and sprayed the perforated sheet and cut edges to blend it all in.
Also for others wanting to know Phanteks were very helpful and reasonable in providing a spare top cover. (I live in Scotland and wanted a spare in case this all went horribly wrong.)
"The top panel for the Enthoo Evolv ATX AG would cost €30,- including shipping. If you agree, we will prepare the payment details to process your request.
SIDE NOTE: For masking off the top radiator section and holes (suggested earlier in the thread) I found Aluminium tape very easy to use. Minimal mess and hassle.