Thanks to all who responded.
The piece in question was a zero clearance
insert for my table saw.
I bought some 1/2 MDF, traced the original
insert and routed the MDF with a pattern
bit. Came out nice.
When I put it in the saw, I noticed that it
stuck up above the table. Knowing that I
needed to cut out where the saw has
supports, I did that with a forsner bit. Still
stuck. I found that my saw has a bit
of a manufacturing "flaw". There is a slight
lip on the bottom of the blade cutout that
is not even with the top. I figured that I just needed
to take out about 1/8 of an inch at these points
I'd be happy. Hence my post.
What I did - I have a drum sander and all I needed
to do was to slightly sand the edges where the
MDF was catching. I did and it now fits fine!
I will be making more of these, so thanks for
the tips about resawing. I think that might work.
I also think if I just routed a rabbet around the
outer edges that probably would work as well.
Again, thanks to all who helped me.