Preston Andreas wrote:

Since the top only needs some adherence to keep the two pieces of mdf
together, I wasn't concerned that the glue was even or that there was
squeeze out. I just drizzled the glue on and did a quick spreading with a
putty knife. I put on the top and found that as soon as the two pieces
went
together, it was like I used contact cement. It wouldn't budge. I had a
very small gap at a place or two, but it was negligible as far as the top
went. Also, I applied plastic lam to all sides. If you apply glue, let
it dry, then apply another coat before putting the two pieces together (as
another poster mentioned), it will give you time to apply clamping cauls.
Make one piece the correct size and the other oversize, then trim it flush
later with a router.

For my next router table, I will build a really sturdy frame, sort of like
a torsion box, that is mortise and tenoned with four crosspieces (allow
room
for the router). Then I will apply one layer of mdf to this. I believe
this will stay flatter longer than two layers of mdf over time. Of
course, care must be taken to make the frame flat at glue up.

How big of a table are you going to make? I thought of doing a torsion box
but made a small (24" by 18") table and even 2 layers of 3/4" MDF feel like
overkill.