I used onshape to create the 3d file.
Sorry for the mess it's my first time using cad software. So I had to learn most of it along the way.
See, get and edit the file on onshape below. If you need help of have questions contact me.
I started with scanning the side of the brake lever on my flatbed. And traced the contour of the top and scanned that as well. This way I replicated the lever in the CAD software.
After that I took the shifter from the base plate and meassured the base to replicate it in the CAD software.
I'll add pictures of the product en process.