Nice! I've been trying to make one of these maps myself, but which base blocks did you use to make this?

Thamk you! I fixed it by saving and then re-checking the CSG.

hmm i am unsure how the platforms can dissapear! All i can say is be sure to double check every step you do by clicking on CSG, metal spots or spawn points. Metal spots can be placed anywhere but will automatically be removed from impossible spots (eg two on each other, inside a rock, inside a structure in any case, in the air etc)so thats an example why you should always double check anything you do.

I am designing a lava system and I placed platforms on the surface and then placed metal spots on them then saved my system and closed it. I re-opened my system to check it again and the metal spots show while the platforms are gone. What am I doing wrong?

Thank you!

what i always do is crack up the water height (i think it's called?) all the way up. if there's still some small islands of land, try a different planet seed! there's 100000000's of options so just type random numbers till your planet is entirely covered with lava/water

How would you turn the planet completely lava? Exuse me if I missed that in the guide.