Well, here's my couple of 'obligatory' tips for Penacoin...
1: Buy a couple. Almost guaranteed you will destroy the first 'batch' within minutes.
2: Make yourself an 'arming' device. Can be as simple as a wine cork with bluetack on the bottom, or as elaborate as you wish. This will make it easier to set up the effect, and also lessens the chances of tearing the rubber. You'll understand if you've read the instructions. Oh, by the way, a lemon is handy here, also...

(throw 'em off the scent)
It's a great illusion!