Pretty much what Nickluvin said above.
There are several steps you will need to go through to achieve this.
1 - Get good scans of both the place where the light needs to go, and the light.
2 - Get those scans in to CAD and fit curves, surfaces, primitives etc. to them until you have a 3D model of both items that is editable.
3 - Design something that mates the two objects together.
The key skill here is the reverse engineering in CAD skill. There aren’t many general guides on doing this on the internet as it is very software dependant. Fusion doesn’t have the best reverse engineering tools but they are good enough. Look up making section sketches of meshes.
There is a quick and dirty way that may or may not work for you. This replaces step 2. Get the scans in to Instant Meshes (free download) and turn them in to quad meshes. You can then get them in to fusion and use the mesh to surface tool to turn them in to reasonable approximations of the surfaces.
I made a post here with a guide on using this method: From scan to CAD. Two ways using MIRACO