Generate CREATE DATABASE FOR ATTACH for all existing user databases
This one does the job for me.  You can tweak the first CTE to include or exclude specific database and it will then generate the appropriate commands.  

;WITH CTE_Databases AS
    (
    SELECT D.name AS DatabaseName
        , D.database_id
    FROM sys.databases AS D
    WHERE D.name &lt;&gt; 'tempdb'
        AND NOT(D.name IN ('master', 'msdb', 'model'))
    )
, CTE_FirstAndLast AS
    (
    SELECT 1 AS CommandStep
        , 0 AS SubStep
        , D.database_id AS DatabaseID
        , D.DatabaseName AS DatabaseName
        , 'IF NOT EXISTS (SELECT TOP 1 1 FROM sys.databases WHERE name = ' + QUOTENAME(D.DatabaseName, '''') + ')' AS CommandText
    FROM CTE_Databases AS D
    UNION ALL
    SELECT 2 AS CommandStep
        , 0 AS SubStep
        , D.database_id AS DatabaseID
        , D.DatabaseName AS DatabaseName
        , 'BEGIN' AS CommandText
    FROM CTE_Databases AS D
    UNION ALL
    SELECT 3 AS CommandStep
        , 0 AS SubStep
        , D.database_id AS DatabaseID
        , D.DatabaseName AS DatabaseName
        , ' CREATE DATABASE ' + QUOTENAME(D.DatabaseName) + ' ON ' AS CommandText
    FROM CTE_Databases AS D
    UNION ALL
    SELECT 20 AS CommandStep
        , 0 AS SubStep
        , D.database_id AS DatabaseID
        , D.DatabaseName AS DatabaseName
        , '     FOR ATTACH;' AS CommandText
    FROM CTE_Databases AS D
    UNION ALL
    SELECT 90 AS CommandStep
        , 0 AS SubStep
        , D.database_id AS DatabaseID
        , D.DatabaseName AS DatabaseName
        , 'END' AS CommandText
    FROM CTE_Databases AS D
    UNION ALL
    SELECT 91 AS CommandStep
        , 0 AS SubStep
        , D.database_id AS DatabaseID
        , D.DatabaseName AS DatabaseName
        , 'GO' AS CommandText
    FROM CTE_Databases AS D
    UNION ALL
    SELECT 92 AS CommandStep
        , 0 AS SubStep
        , D.database_id AS DatabaseID
        , D.DatabaseName AS DatabaseName
        , '' AS CommandText
    FROM CTE_Databases AS D
    )
, CTE_Files AS
    (
    SELECT 10 AS CommandStep
        , ROW_NUMBER() OVER (PARTITION BY F.database_id ORDER BY F.file_id) AS SubStep
        , F.database_id AS DatabaseID 
        , D.DatabaseName 
        , CASE WHEN ROW_NUMBER() OVER (PARTITION BY F.database_id ORDER BY F.file_id) &gt; 1 THEN '        , ' ELSE '      ' END + '(FILENAME = N' + QUOTENAME(F.physical_name, '''') + ')' AS CommandText
    FROM sys.master_files AS F
        INNER JOIN CTE_Databases AS D ON d.database_id = F.database_id 
    )
, CTE_AllTogether AS 
    (
    SELECT CommandStep, SubStep, DatabaseID, DatabaseName, CommandText
    FROM CTE_FirstAndLast
    UNION ALL
    SELECT CommandStep, SubStep, DatabaseID, DatabaseName, CommandText
    FROM CTE_Files
    )
SELECT * FROM CTE_AllTogether
ORDER BY DatabaseID, DatabaseName, CommandStep, SubStep;