I made my own from sheet aluminium.
First make a cardboard pattern.
Cut out the shape with tin snips. hacksaw blade.
Folding into shape needs some planks clamped each side.
The curly bit at the back was made with a separate strip of alloy, bent to a channel,
then using pliers on the side walls to make a crinkled effect, the curve could be formed.
The part was fitted with tiny self tappers every inch along.
finally sprayed black to hide my poor workanship!
Mick