i know essentially what engine dowelling is, ive done my homework on the search and am planning on building a 12at, but for the life of me i cant figure out what engine doweling is, and why its so expensive,

can i do engine doweling myself, what would i need, i want some professional opinion here, ive been reading about different aspecets of making a 12a run realiabley with boost, and i found this would be very neccisary any help is great