It's not quite clear to me which software it is that you're interested in making. The 3d printing software stack consists of a few entirely separate efforts. Namely: scanning or modeling (e.g. Solidworks, Blender, OpenSCAD), slicing (e.g. Cura, Slic3r), printer host (e.g. Pronterface, Octoprint) and firmware (e.g. Smoothieware, Marlin).
Here's a short overview (although their "Pre-press Preparation & Repair" section is unnecessary now AFAIK). Also, some components of the stack are different based upon the method of printing you're using (fused deposition modeling v.s. resin printing, etc).
Cloning the entire stack is unrealistic and as you can see, there's already at least 2 of everything (there are
way more implementations of each piece of the stack than what I listed). Most of the development for these individual components occur on Github and/or Google Groups. So if you're interested in joining one of those projects, either search for one of Github & navigate to one of the developer's profile to find their email address & message them, or head to Google Groups and search for a group related to what you're interested in.
