Thanks for the support guys,
I'm sorry I don't have detailed drawings but I'm happy to provide measurements if you need anything.
I decided to make my own throttle which in hindsight may have been a little weird as they make some very nice ones but I was firmly in DIY mode at that stage.
I made up a prototype first just to see how things felt. I had looked a a few in stores to get the sizing.
From that I used pine (easy to work and shape) to rough out a shape. I added an extra piece on the top to allow room to fit the switches.
Using a wood rasp shape the corners and get the size right. Finish wasn't important here yet as it was going to have automotive filler applied .
I added ice cream sticks as an easy way of layering up areas that were too low. It was still a in two halves as this stage as I needed to be able to cut access holes internally to run the cables through. It was later glued together.
Filler applied to any areas that need it.
Primer applied ready for finishing coat.
Switch plate to house two momentary and one rocker. Aluminium plate used.
Final finish and assembled.