As a woodworker, I have a few thoughts. When you mention 2" x 2" squares, I assume you are thinking about using 4 for each stand (1 at each corner). A single 2" post would by much too flimsy for even an M3.
As far as using a soft wood to eliminate vibration transfer, I think it's more important to use a lot of mass and decouple it from the floor with spikes or pads, depending on the floor material. Most commercially available speaker stands are pretty heavy. This would also serve to make them more stable. I'd suggest using hardwood because it's more durable, stable and generally easier to work with.
My DIY stands are solid cherry with a natural oil finish. Over time, they darkened to be a pretty close match to Boston Cherry (which I think is beautiful even though I have Mansfield Beech speakers). Inside the post is a 4" cast iron pipe filled with sand. They weigh about 40 lbs each. I have the M22s secured to the top with double sided tape. I was a bit apprehensive to do this at first, but when I removed them after about a year, there was no damage to either the speaker or stand.
