I was thinking of making one for my SIIA, should be easy enough.
Possibly gonna get a southdown wing moulding as they look the biz, get a metal pipe from B&Q as the plastic drainpipes look, well plasticky - they have black powder coated metal pipes they sell as worktop legs for £8 that look the perfect size, scavenge some flexi-hoses from a scrappies and bung my cone-shaped K&N filter on the top.