First step! Find wood. We built our butcher block out of cherry wood. Hard wood is best for butcher blocks (think fruit bearing trees) so they don't get marks and dings so easily.
Next the cuts. We measured and cut the wood a bit longer than the final length.
Glue time. Don't use too much, but not too little. We did both. Too much left us with glue pouring out the cracks when it came time to clamp and not enough left us with a broken butcher block....(fixed easily by glueing it a second time). Go for a thin line down the entire length of the wood. Go ahead and use a couple pieces of scrap wood to test it on. Put the amount you think is right then clamp it together. You will know soon enough if you put too much.
Clamp it tight! We learned some good lessons here. Best to get the planks of wood as level as you can get them. Place the glued board on a flat surface with some weights on it, or clamp some 2X4's on either side of the butcher block perpendicular to the cuts. We did not do this and the result was ALOT of sanding to get a level flat surface. The alternative is running it through a planer, which you probably don't have if you are reading this...lol
Wait 24 hrs and give it a good sand! Use some rougher paper to get it flat if needed then switch to some finer paper to get the smooth finish.
Apply butcher block conditioner (yet to come for us) and there you have it!
We are still waiting for our sink and stove to come to install the block into the van but this is what it looks like for now.