Below is a page that tells a story of a device that caused a building to shake, but the device could fit in your pocket. The device was able to apply small, hammer like impacts, with timing adjustments.

So I have made my first simple modeling of an upright structure on a solid base, shown below.

The base is 3/4in particle board with 1/8in black plexi as a top, level mounting surface. The lower brackets ar 1in angle aluminum and the plexi strip is 1 3/8 in wide and 1/8in thick. These numbers will change to find the right combination to get the desired movement.

I will be using a coil that will pulse a magnet that will be attached to the lower end of the plexi strip to simulate the tapping effect. I will also try actual mechanical(solenoid, or coil driven lil hammer) tapping,  and tune the taps to the resonant freq of the upright structure to get it to oscillate.

The goal is to to see if first we can get the upright structure to get moving with minimal input. Then test to see if we can tap that movement energy to energize the tapper. 

Ok, Im going to relax a bit. had a hectic day. Was up till after 3am in pm.  Not my usual habbit.

This basic setup is just an RnD thing to get the feel for what is going on and what changes need to be made for better results. Then will build a more refined setup based on what I find here.

Lol, worst pics my camera ever took.  Its all about the lighting.

Mags