[mengtian]

My neighbor was going to throw this out. Kitchen cabinet top. 31" x 25". I thought about using it for a router table. If I use it should I brace it underneath to keep from warping in the future? Still has plastic on it and no scratches.

 

[Gary Beasley]

I'd look for something bigger. A good 30 inches will give you more workspace and stability. I made mine from an old office desk.

 

[knotscott]

Should work well if supported.

 

[jschaben]

My neighbor was going to throw this out. Kitchen cabinet top. 31" x 25". I thought about using it for a router table. If I use it should I brace it underneath to keep from warping in the future? Still has plastic on it and no scratches.
View attachment 73061

I'd trim the profiles off the front an back edges and glue it to a piece of 3/4 MDF for added support and stability. Unless I miss my guess, that has a particle board substrate so the MDF would give it stability more than anything. I'd seal all the raw edges though. Size is fine, my Woodpecker top is 24 x31 1/2.

 

[MORRIS76]

It will work fine after trimming. If it is particle board I'd add at least 1/2" MDF as additional support, seal the particle board edges and band it with hardwood. I think the size is ok unless you have a large shop and have room for a larger table.