How big of a piece of material are you trying to mill. seeing as most end mills are like 2in that’s really about the maximum plunge depth you’ll be able to achieve. if you’re talking about milling large items then why not go the route some are and put the legs through the table so it can be raised and lowered. or remove the inner section of table completely so you can have limitless options for materials, making the waste board completely removable. this way if you have something tall you want to engrave and it’s not going to fit on the table you can just add supports for it from the floor and get it in position that way.