Scratch cards seem to have become a very low return product, and it is difficult to see how to recover my investment when 100% losses are common. Coins are popular for scratching, so maybe I'll discuss the purchase of bags of coins from the banks, and checking them for rare coins. At least I'll have a bag of coins to the value of my purchase if I don't find anything.
On a totally different topic, I've bought a couple of classic Volvo cars, and they are already showing a small notional profit. Maybe I could discuss the removal of scratches in the paintwork. After all, the object of this site is to scratch up enough money to buy some woodland to preserve. Scratch used to be a slang term for money to buy food, but I haven't heard it used in the context since I was a kid.