So here is what I am thinking:
We'll add two new nodes: moon portal blocks, and mars portal blocks.
(it will still be possible to cheatingly get obsidian, but that is difficult because of the 8:1 portal link ratio, and the obsidian comes form the base mod. Also obsidian is not nearly as valuable as steel and bronze are)
the crafting recipes will be:
steel block + mese crystal = moon portal block
bronze block + mese crystal = mars portal block
I will make textures and indicate where to place them, etc. Or I could just copy the files, edit them, then host them on my github, them you can download them and replace the original files.