mkr5000 wrote:
I really need to route it because I need to plunge into it and don't
want the slot the total length of the board.

Been a long time since I've done this, so can't remember if I can
route that wide a slot (3/4") -- just 1/4" deep or even less, just
enough to fit another piece of 3/4" plywood into.

Do they even make a 3/4" bit or would I have to do multiple passes for
both the width and depth? (yuk).

Sure assuming your router is up to the task.

Altho w/ today's ply you'll more than likely want a 23/32" bit
specifically for the purpose.

Even there you'll want to make a test cut and see if that matches the
specific piece sufficiently well.

So, all in all, you may well want to consider one of two options -- use
the narrower bit and make the cut in a couple of passes to ensure the
proper fit or,

b) cut a rabbet on the inset piece of a specific thickness and use the
proper bit size for it instead.

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