Hey Mike,
you can attach any type of limit sensor to a Masso G3 controller, e.g. inductive proximity sensors → give the best (homing reproducibility) results. Yes, you’ll need a few 3D printed parts, but more than → one forum user has made such parts for limit sensors and could be willing to make such parts for you.
On these photos, @TMToronto attached the inductive proximity sensors to a MASSO G3.
I’m sure that if it’s just the limit sensors that you need, you will get help on how to wire them to the Masso G3 in this forum. The only problem to solve would be to find someone who 3D prints you the parts for attaching them.
Another question: If you buy an Onefinity Elite machine, you not only get the Masso G3 and the Onefinity photoelectric homing sensors, but you also get the components that are listed → in this post. If you don’t buy an Elite Machine, do you intend to procure / manufacture all these components yourself? Or do you already have some from your previous Masso G3 build?