Alloy plant

So I’m about to start a new colony and my nation absolutely sucks with alloys, but I don’t really know how to make a stable planet that would do that cause half the time I end up needing like 85 things so there’s never enough space for the specific thing I need also by the way for this entire play through I’ve had three planets and I’m thriving up until this point where I’ve been preparing for a war for like 500 years and now I have to work on megastructures and I’m pretty sure there’s one that makes alloys so that’s what I’m going for but it hasn’t popped up in my research yet so I’m just trying to get the Ascension Park for megastructures so I’m trying to finish up a science Nexus