Recently I have been designing some 'Laser Cut' radiator cover screens. Please see attached a dxf file with which you will find a block of the original design and a block of the grid layout which you can use to design your own cover screen design with QCAD .
The grid can be used to design cover screens up to 900mm x 610mm (with a margin of approximately 20mm). Your own design of shape/s works best if they fit an individual size of 21mm x 20mm.
Simply copy and paste your shapes to the grid intersections.