I use 2 methods for multi-color prints. The one I used for "Oink" involves 2 plates for 2 colors. This method allow me to do multiple editions and re-use my plates.
The other method is the suicide method. Which only involves 1 plate. Its called suicide because there's no turning back. You carve the plate till there's nothing left. So you can only produce limited amount of the design, and only have 1 edition.
Both methods requires registration (line-up) which I suck and hate. But I've finally came up with a really cheap method. If you want to use multiple plates you have to make sure they are the same size. Once when you put the first plate down. You mark the corners with a pencil. Just 1 dot on each corner. Then when you're printing the second plate you can match up the corners. To be able to match up easily and without smudging I use a see through (clear) ruler. I tape the ruler down. Then line up the dots of one side. Then I can place my plate down without too much fuss.
Its hard to see the dots but they are there. Here's a picture with the ruler and the dots lined up.
After lining up the dots I lined up the plate with the ruler and the top left corner dot, and print.
This print is still in progress because it takes soo long to dry. I will put the entire process with more pictures later. I hope this help you guys out there that are poor and trying to find a cheap way to get things lined up :) ~~~Have fun~~~!!!!