Hi Dizza. As promised, here is the composite panel manufacturer. It's a product by Ullrich Alluminium. Rigid as hell and light as too. You can also countersink it, but practise on a little bit and get your drill sharpened with minimal taper behind the cutting edge or blink and you'll have a hole the size of your countersunk rivet!! I used 5mm CSK blind rivets from Wurth on my camp body. Here's a pic which has the phone no on the removable wrapper!!

