I have found a way to generate obsidian, in a renewable way, fairly early game. It does not need a smeltery, vat, Rotarycraft, or any of that stuff, and does not consume lava or any other resources once it is set up. All you need is : 1. 1 Terrain smasher 2. 2 Project Red repeaters 3. 1 piston 4. 1 timer 5. 1 lever 6. 1 bucket each of lava and cryotheum 7. 2 pieces of red alloy wire Assemble as below: The cryotheum stops one block before touching the lava and where the obsidian is located is usually where the last block of lava flows when the obsidian is not there. Both repeaters are set to 16 ticks, and the timer is set to 4 seconds. The piston is facing down at the last flowing block of cryotheum, and of course the terrain smasher is facing the obsidian block, set to High redstone control. The timing is set up with the piston so when the obsidian is broken the lava flows into position first, then the piston releases and the cryotheum flows, and upon it's flowing it's area of effect freezing turns the flowing lava into obsidian. If the lava has not flowed first then it will generate cobble instead of obsidian, it can be quite finicky if you do not use the timing above. (this setup does rarely spit out a cobble or two once in a while.) This is just a basic setup, I am sure with a little time I could make a large obsidian factory, but this is good enough to just slowly but surely churn out obsidian (probably making more than I need anyway).
Yesterday people were looking for an obsidian generator, but were not happy with their options. I read about this one, but never found any plans, was a bit tricky to get it to work right.
Oh, well I an ianthenoob were clearing out a big pool of water at my place, and we were using cryotheum and lava together. Obsidian ensued.
My setup does not create free obsidian like yours, but I did set up an ME setup to create obsidian for me, at a rate of about one or two per second. An Autonomous Activator uses lava buckets on a space just below falling water, which instantly turns into obsidian. On the same square an ME Transition Plane eats the obsidian. I have lava and lava buckets already autocrafted in my ME system, nearly as fast as they can be placed by the activator.
Now that I have done some thinking I may have a few ways to make this system more compact, I will update this post when I have finalized the design.