Thanks for responding, Hand-E-Food
The code is kind of convoluted, but basically it generates 'true' random points spaced 8 tiles apart in a grid, then all other tiles are a height gradient in between.
There is no coded prevention against inaccessible areas, but the player can mine through rock so it should be fine.
As for phase 2, that's what I'm still trying to figure out - probably something involving the combination of parts to make new things.