Have a look on DW for homemade ultimate swirl spotter torch.
It's basically a sungun but for £20 instead of £400. You need a cordless drill (any will do), crack it open and remove the motor. Replace with a bulb holder and a solux bulb. The switch is a variable rather than on/off so you can vary the brightness and hence highlight swirls in different ways. Honestly, if I fan do it, so can a three fingered chimp with parkinson's, so none of you should have any excuse.