> I'm ashamed of myself for not coming up with this sooner

Shame, thy name is Denny

> This has been done. You can buy one retail at major sporting
> goods stores for a few hundred bucks, a baseball pitching machine

Boy, did I ever get side-tracked ;-) but it's all food for thought

Found the ball's weight, 5.12oz (145g), Rule 1.09

http://mlb.mlb.com/NASApp/mlb/mlb/official_info/official_rules/objectives_1.
jsp

(must remember to read MLB rules and definitions before
next World Series so I know what the hell the commentators
are talking about)

AFAIK there isn't a pneumatic pitcher for baseball. The two
types I've seen are spring-operated (a revolving disc stretches
a large extension spring until a trip point is reached, then the
ball is thrown by an arm) and contra-rotating pinch wheels, one
of which I know is a Jugs used by NZ Cricket in Auckland

http://www.thejugscompany.com/products/baseball.cfm

Now there's even one for soccer balls

http://www.thejugscompany.com/products/soccer.cfm

I've seen a spring-operated boot on TV. My brother the soccer
coach went ooooh and asked me to make him one. I didn't

But getting back to air..........

There is a pneumatic type for tennis balls, The Lob-ster

http://www.tennis-ball-machine.com/catalog/Tennis_Ball_Machine_Superstore/Lo
b-ster_401_Tournament_Model_Tennis_Ball_Machine

(The Lob-ster is quite cheap compared to the Prince units, which
can be up to US$3500 and I don't think they're pneumatic)

According to

http://www.itftennis.com/shared/medialibrary/pdf/original/IO_1404_original.P
DF

a tennis ball should weigh only 2oz (57g)

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