I'm going to be bending my own "base bars" this week. It will be a cross between an aero or die (AOD) setup and a Scott 100k. The Scott 100k are 11 inches wide outside to outside. Mine will be about 8 inches outer to outer. Extensions will be 6 inches apart inside - inside.
As you can see from the above, the tube will be placed on the left side of the "jig" and then wrapped around the center block. This will create the U shaped basebar. The tubing I'm using is 25.4" outer diameter with 22.2 internal diameter-----aero extensions will slide into it.