I wouldn't know where to get hold of that over here in the UK.
You can make your own by thinly slicing a piece of 1x lumber, and then sanding the top two edges slightly to round them.
That's all that piece really is.
The hemlock is nice because it's more flexible than some other woods, so doesn't split as easy.
As far as using the magnets goes, they are standard ones you'd see on a bathroom cabinet, stereo cabinet, etc...
I screwed the magnet part, one on each side of the cabinet, and glued the metal part to the back of the lexan.
The nice thing is that I don't have to do any unscrewing etc... to access the marquee light.
I can just pull that panel off of there.