The panels are available from shapeways, above is the original packaging it came in, it was also wrapped in a balloon/bubble wrap thing to keep it safe, all the way from the Netherlands.
Installation is best done by flexing the panel a little, i made the clip a little long so it sits very securely, but it's just a little too long to push fit. Don't be put off though because it's incredibly easy to fit in the case and to remove it. Its made of a tough, laser sintered nylon but it has some springy flexibility to it, its not as brittle as ABS or many other casing materials.
It also means the Amiga runs cooler, helping to ensure a longer life, and I had some issues with my accelerator card overheating with some 3D games, like my favourite game of all time, Frontier.
Now, I can play that game without the colours going all funny and crashing after 20 mins.:)
Get yours from right here buddy! A1200 Expansion Port Trapdoor Cover