You can easily start up a WebLogic Server on an empty directory and it will create a domain. Here is another way to create WLS domain structure folder without actually starting up a WLS server.
# Usage: wlst.cmd createDomain.py <domain_home> <port> <password>
# NOTE: the <domain_home> must be a absolute path.
# Example: C:\wls12130\wlserver\common\bin\wlst.cmd scripts\createDomain.py C:\data\wls12c_domains\dev 7001 weblogic1
import os, sys
domain_home = sys.argv[1]
domain_name = 'mydomain'
port = int(sys.argv[2])
password = sys.argv[3]
readTemplate(os.environ['MW_HOME'] + "/wlserver/common/templates/wls/wls.jar")
cd('/Server/AdminServer')
set('Name', domain_name + '-admin')
set('ListenAddress','')
set('ListenPort', port)
cd('/Security/base_domain/User/weblogic')
cmo.setPassword(password)
cd('/')
set('Name', domain_name)
writeDomain(domain_home)
closeTemplate()
exit()