Never tried any Wagner. I've borrowed a professional ($800) paint
sprayer from a neighbor, and it works GREAT.

My vote: A cheap Sears router (1/2 or 3/4 HP) from the early 90s.
Height adjustment is done with a plastic ring that's clamped onto the
base, and goes all the way around the motor. The motor itself is in a
plastic housing, and has a spiral plastic thread that engages the
height adjustment ring - or not, depending on the phase of the moon.
And the height adjustment ring isn't tight, so it spins around by
itself. All this gives rise to ...

ARHA - a feature available only on Sears routers:

Automatic
Random
Height
Adjust

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The address in the header is invalid for obvious reasons. Please
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Ralph Becker-Szendy