Solar Powered Light Deflector

I bought this in the summer. It has a solar panel on the top and a ring of lights around the inner circumference. The one in the photo lights up because it backs onto the wall. Mine is backed onto a trellis and therefore doesn't reflect the light as it should. To rectify this I am planning to make some kind of plate that is shaped precisely to attach to the back of the feature. Originally I thought of something like a copper sheet. I have also thought about different types of metal and acrylic backing. I would appreciate any experience on what materials are suitable, affordable and easy to work with. Alternatively I have seen companies online that will custom cut acrylic sheets to fit. I haven't looked into it yet but I would imagine that that option would work out quite expensive.

G.

 

Cheaper options include plywood. Cut out the required size of disc, cover inside and out with polyurethane varnish and a final coat of acrylic paint of your chosen colour.
Of course I say this as some one who like the diy arts and crafts and hates spending money, so I've got an endless supply of off cuts and tins of paint and coverings.
Another option, depending on the size you require, is a 25l plastic storage container...the jerry can type. These are normally HDPE so can be cut and flattened fairly easily, they come in different colours and can be found quite readily

 

A poundland tin pie shell pan might work. They are much tougher than they look?