A step drillbit was then used to accurately widen the button holes to the right size.
An additional hole was added for the tablet charging cable.
Wire harness in place.
I drilled a hole first and then, using the vice and a piece of wood as a guide, I gave it the right shape. The gap is wide enough to accommodate even a 10″ tablet.
For now it holds an old Google Asus Nexus tablet
An angled USB charging cable makes the connection looking quite neat.