Thanks for the responses, everyone. I would do it myself, except for the fact
that I know almost nothing about metalworking or welding. All I'd be able to do
is paint Plus, if there's any demand for the product, we'll need the items
mass produced.

One component of the furniture will be height adjustable tubular legs, with one
tube fitting into a larger one, being locked in place by an adjustment knob or
screw. Does anyone know the best way to implement this? I've seen various
furniture pieces with extruded nylon or plastic sleeves/liners that fit into
the larger tube, acting as a cushion/bearing against the smaller tube. Sort of
like a hollow end plug. Can anyone suggest a source for these items? Also,
what's the best way to thread the hole in the larger tube to accept the height
adjustment screw? For heavy loads, perhaps it would make sense to drill a
series of holes in the smaller tube and use a screw or pin that would extend
through both tubes. Or perhaps someone knows of a source for ready made
assemblies like this?

With respect to the finishing process, I've check with local shops that do
blating and powder coating, and all were expensive. I'm wondering if there are
larger shops that will group small jobs together with a larger customer's
powder coating job, in order to reduce setup costs. Thanks!