On Thu, 21 Sep 2017 08:06:07 -0700 (PDT), "Dave, I can't do that"
wrote:

Guys,

I hate to mention the topic of wood, but I want to mount a 3D-printer on a flat stable base so I can move it around without disturbing the delicate (poor design) setup.

I cannot afford a 24" square piece of 1/2" aluminum and cannot lift a 24" square piece of 1/2" mild steel.

So, I am looking at 3/4" MDF, OSB and plywood, but open to other helpful suggestions, but low cost is the operative.

Which of those options is likely to be the most stable? The machine has many brackets for attaching to a base, so flexing and stability is at the pointy end.

The MDF might be the flattest and most stable, but it's extremely
susceptible to moisture damage.

Neither the OSB nor ply would be perfectly flat, but you probably
don't need perfect flatness.

Of the 3, I'd probably go with the ply. I love Waterlox Original (a
fairly clear tung oil finish) in satin sheen, so I'd put several coats
over the wood to keep any moisture from warping it.

--
Stoop and you'll be stepped on;
stand tall and you'll be shot at.
-- Carlos A. Urbizo