TOP MARKS to German BMW accessory firm Wunderlich. They've come up with these rather tasty clear plastic cylinder head covers for the air-cooled R1200 engine. A straight replacement for the stock parts, they fit the air-cooled four-valve flat twin R1200 range - so the 2010-12 GS, 2010-13 Adventure, 2011-2014 R and 2010-13 RT and, of course, the current RnineT models.
Dubbed the X-Ray covers (see what they did there??!!), they're made from 5mm thick 'technopolymer' plastic. Wunderlich claims they have a special coating that resists scratches and wear, and are suitable for use between -50°C and 180°C, so should cope with any temperatures you're likely to come across. They show the camchain, rockers, camshafts and valves, all bouncing up and down like billy-o, which will while away many a long hour at the pub, showing passers-by, no matter how reluctant they might seem.
They're not cheap, at €749, including new gaskets. And if you don't have them already, we'd be looking to fit some engine protection bars as well, to keep the clear plastic covers safer in a spill. More info here.