GCode to cut a level working bed?

Mostly Printed CNC - MPCNC Troubleshooting
1

I want to cut a 10" x 10" level spot on my work surface. I have a heated plate and glass I would like to insert so I can attempt some 3D printing.
Since I am not really up to speed on using the CNC software yet (Estlcam) I am not sure how I should go about this. I have a nice oak plank that I want to use as the base. I also have 1/2" and 3/4" flat end router bit that I could use to cut the flat area. I am using a Dewalt 660 so I think the 3/4" bit will work fine.
I would guess I should make a couple of passes to get it nice and smooth.

Do you guys have any tips you can share?

2

It should be as easy as creating a solid square in a cad software (freecad for example), then in ESTLCAM just using 1mm (maybe 2mm) depending on how flat it already is engrave, and set the router bit perfectly on top of the wood (flush) and let it go. it will go down to the designated depth and engrave out the whole thing.
I plan on doing that simply to make my bed perfectly level, but you have a great idea about putting in a piece of glass. thats very smart. If i turn mine in to a 3d printer i will do that too (except ill make mine huge. i already have a 12x12 3d printer haha