D22 Navara ashtray replacer

My adventure vehicle is a 2005 Nissan D22 Navara. Soon after purchase I removed the whole ashtray mechanism and decided to create something to fill the open ashtray holes.
I want to add a friendly horn system to my car where one button can play a friendly sound through a horn speaker (like the C3PO noise) to alert people to my presence in a less threatening way than tooting the standard car horn, another button to 'double-toot' the horn, another button to activate air horns, etc.

Refer to the photos as part of the description.

The switches that I used are momentary action push-buttons purchased from Jaycar (Australian Electronics supplier). The mounting holes are 20mm in diameter to suit these switches, but anything that fits in a 20mm hole can be mounted). There is one single mounting screw to hold the part from behind the facia. The screw that I used is about 10mm in total length, and about 3mm in shaft diameter (including thread). I had to place a washer under the screw head.