BILLY BOOKCASEBUILT INS
Pull off the baseboard (if needed) and assemble the bookshelves without the doors.
REATTACH THE BASEBOARD
Line the bookshelves up, take measurements, and cut the baseboard to fill in the gaps. Then use your nail gun to reattach to the wall.
Nail the bookshelves together, attach each unit to the wall, and put the doors on.
See the full tutorial at loveloveloveblog.com