The housing for the button
I used a 55mm Pipe Stop End. I sand the piece to remove the irregularities.
In the pipe stop end, I glued a 35mm Piezo element inside it with epoxy glue
Because I need about 6 buttons, I decided to create a PCB.
I used DipTrace for the layout, and I ordered them at http://www.pcbway.com/
Paint the Pipe Stop End 2 times with Aerosol spray filler. Than 3 layers of yellow spray paint.
To finish I put 2 layers of clearcoat.
To mount the PCB, I used a piece of plastic angle and cut 2 small pieces of it. With Hot glue they are kept in place and with epoxy glue they will stay there forever.
I drilled 2 small holes in the angels to hold the PCB with screws.