The ideas here motivated me to think of one: bike inner tube!

I can't remember the diameter, but it's not the biggest one. Anyway, I cut the tube to fit in the little slot underneath the button. Then, double up the tube so that it wraps around the lighter tightly. It works well! Plus, it's extra tinder. I can still press the button if I mash down hard, but it's a lot harder to push with the inner tube there. (Richlacal did mention inner tube above, but he didn't hone in on this method.)

Holy cow, this has been a useful thread!