My mandolin is a poor substitute for a drum...

I am more than a little reluctant to knock, hit, rap, strike or whack my fragile mandolin for the otherwise most enjoyable "Porque Es Alli".  Though I play a cheap instrument, I still don't want to damage its finish.  If I played an expensive axe, I'd feel that way even more.

A strip or two of duct tape over the impact zone would make my mandolin a less-fragile "drum".  But there are some obvious drawbacks to this. 

I've been tapping the top of my (inexpensive, replaceable) bridge with my fingernails or my pick, which creates a loud-enough sound.  Hitting the mando top creates a lower thump, but again, it has the potential for damaging the finish.

If I need to play percussion, I'd much rather bring a drumstick and a wood block, or a pair of claves (which I own), and get the job done right.  You get a way bigger sound when you hit an instrument that's designed for the purpose.  All due respect to the talented composer, but if we need a percussion instrument, let's play a real one, what the heck.