As someone who JUST (No literally, like 10 minutes before this post) made the GraviChestplate, I have to say it takes a lot of materials and a lot of patience. However, here is one way I found is easy to harvest not only the gratuitous amount of materials for it (tin, copper, iron, etc) but also the UU Matter. Now, keep in mind, I had made the Ultimate Hybrid Solar Panel first, as its essential to this process.
1) Make an eternal daylight Mystcraft world. I made it a single biome Mushroom Island biome to keep pesky mobs away. (I managed to make it almost perfect, but I did have Hunger 3 going, probably due to bad writing)
2) Set up a 60x60 quarry area. I used a modified Electric Engine (with circuit board to increase output to 12MJ/t), this was powered by a *Hybrid Solar Panel*.
3) Set up 3 chests (preferably the obsidian chests due to massive storage size), use a diamond pipe to filter items. I usually specified bees into one chest, and left the second chest as my everything chest.
4) The third chest I specified to receive dirt, cobblestone, gravel. This is important, as this is your recycle chest.
5) From that chest, pipe items to 5 recyclers (which I powered via 2 Advanced Solar Panels).
6)Pipe each individual recycler to a seperate singlular chest (regular chests work for this). I have the recyclers all feed into one pipe that leads to the chest.
7) Scrap should now be pumped into that chest continuously.
8)Now pump the scrap out of that chest into a Mass Fabricator. This Mass Fab should be powered by the Ultimate Hybrid Solar Panel.
9) Finally, make one last pipe from the Mass Fab into another, final wooden chest, to pump out the UU Matter.
Note on pipes: For powering the wooden pipes, here is what I did:
For cobble/dirt/gravel chest: 4 Redstone engines (you gotta be sure you pump stuff out at steady, but not too fast rate)
For recyclers: 1 Redstone engine for each wooden pipe, 5 total. (You'll never really have to worry about scrap overflow as the 1/8th chance of producing scrap keeps it minimal)
For Scrap chest: 2 redstone engines. (You won't have overflow at all, but it keeps the scrap continuously pumping to the mass fab)
For Mass Fab: 1 Redstone engine. The rate of UU matter production will never exceed the rate at which that pump can spit stuff out.
Also note on cobble/dirt/gravel chest to recycler piping: I have the pipe heading to the recyclers, but I also have it looping back to the chest to carry any overflow back. It will be pumped out again upon arrival.
And essentially, that's it. After going to sleep for the past 8 hours, I woke up to a wooden chest filled with 8.5 stacks of UU Matter. Is this the most efficient route? Most likely not. Is it relatively easy to accomplish? After the initial grind to get the Ultimate Hybrid Solar Panel, yes. And obviously feel free to improvise on any of these things. I do feel its necessary to mention that the 12MJ/t output on the electrical engine is ideal. If you supercharge the quarry to 50MJ/t, you could find overflow problems with the chest without upgrading those engines.