What's involved in "rebuilding" a crank?

[Greasemeup]

Just curious what a typical rebuild is, what are the goals of a rebuild?

[hybrid]

Basically replace any parts that are out of spec (cank bearings/big end bearings/rods/thrust washers etc) and then press it all back together and true the flywheels to spec with a soft (copper etc) hammer/drift.

[BRG1200]

Have a look on youtube, not sure here are any greatbsbecrets revealed like trueing with a copper mallet etc, but there are a few vids showing cranks being pressed together etc