Yep stone barrels, good for making end stone as well. Also, once you have adv gens, you can get obsidian as a by product.
I am working on my reactors now, trying to decide if I want to just make my fission reactor bigger or go for the fusion reactor. The fusion clearly outputs much more power, (which minechem needs desperately, especially for those crystals), but seems like it can be quite tricky to get it to run efficiently. I am leaning towards just making my 5x fission into at least a 11x, kind of a hammer approach but
. I suppose the real downside to a huge reactor is the cost, materials plus fuels, well that and the small chance for an epic explosion...heh.
Also, I was watching some tutorials on the RFtools stuff, are all the dimension building things available? Seems like that would be really wild, though not sure where I would start looking to find the unidentified dimlets.