...Wood is ok for templates, but tends to burn, so maybe one time only?
AH! Now your talking.. I usually used metal guides against the tip. Wood on the next bit up would (Oh!, the pun) be OK .Depends on; what the wood is, whether you're angling straight down (holding the torch at an angle is more likely to heat the metal that the wood is sitting directly over), and how fast you travel.
I find the bits of wood tend to last a fair few goes - I've been using offcuts of cheap laminate flooring which seems pretty heat resistant.
Oh - and you're running the white cup along the wood, right, not the metal tip?
what sort of air flow rate do these use the ebay ones need ?