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.

Thanks

None is really stable if you have a big load on it, but thickness
makes up for it, if you don't mind gluing together a couple of sheets.

If the situation will handle 1-1/2" of thickness, I'd use two sheets
of 3/4"melamine-covered MDF, glued back-to-back. The melamine on BOTH
sides of the sandwich will give you a lot of stability from humidity
changes; the 1-1/2" thickness is stiff, and it looks nice.

--
Ed Huntress