Ed, you gave me an idea an here's what I came out with after playing with the Jeff's splitter. Dohsan would be able to change the word delimiters as he considers correct without much problem.

It's a simple query but can be easily converted in a iTVF.

DECLARE @pString VARCHAR(255) = 'this is a 3d-printer from wahsington d.c.';

--===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000...

-- enough to cover NVARCHAR(4000)

WITH E1(N) AS (

SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL

SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL

SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1

), --10E+1 or 10 rows

E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows

E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max

cteTally(N) AS (--==== This provides the "base" CTE and limits the number of rows right up front

-- for both a performance gain and prevention of accidental "overruns"

SELECT TOP (ISNULL(DATALENGTH(@pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4

),

cteStart(N1) AS (--==== This returns N+1 (starting position of each word)

SELECT 1 UNION ALL

SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(@pString,t.N,1) IN(' ', '.', '-', '''')

)

SELECT (SELECT CASE WHEN s.N1 IS NULL

THEN LOWER(SUBSTRING(@pString,t.N,1))

ELSE UPPER(SUBSTRING(@pString,t.N,1)) END

FROM cteTally t

LEFT JOIN cteStart s ON t.N = s.N1

ORDER BY N

FOR XML PATH(''),TYPE).value('.', 'varchar(255)') ProperCaseString

;

EDIT: I reduced the datatypes for GREAT performance improvement.