I’ve ordered an AltMill 2x4 that I hope to receive this summer. One contender I had been considering was the Shapeoko. The only thing that I will miss from that is their “Hybrid Table”. Instead of the two MDF layers that Scienci recommends for the AltMill, a base layer of aluminum with built in work holding, and then easily replaceable 3" wide waste-board strips on top of that seems like a fabulous idea to me. I am curious if anyone has attempted to create a more Shapeoko style table for the AltMill. It does seem that Carbide 3D sells the Hybrid Table aluminum extrusions for $15 each. at $180 for the required 12 of them, that seems like a bargain, but I have no idea how difficult it would be to properly attach them to the AltMill. Has anyone here gone down that route or done something similar?
Any reason you wouldn’t just use t slot and MDF to do the same thing ? The shapeoko setup is very common, with the exception that most people wouldn’t use that many t slots due to the cost. The OEM design of the Shapeoko is different, but you can do the exact same thing yourself without having to pay for their custom stuff.
My biggest justification is because aluminum is permanent and MDF is temporary. The base layer screws in from the bottom of the machine and, for me, would be a major PITA to change. An alumininum base layer will not be harmed by stuff like bit-lubricants for cutting aluminum. It will not be damaged by repeated screwing in of replacement top layer waste boards. An aluminum base layer would give interesting options for quickly and easily attaching and removeing the Vortex 4th axis. When using a laser, there would be no flamable layer underneath the work piece. Oh, and I just think it’s cool. 
That’s fair, I can get behind that. It’s not exactly what you want, but here’s what I did which ended up with a somewhat similar setup:
I used MDF as my table top, milled a grid of holes in which I installed threaded inserts, and used those to bolt down my actual wasteboard slats. The slats are designed to be able to be machined on a 45 degree angle so I don’t have to make them manually. I cut thru holes in the slats so that I have access to additional threaded inserts in the table top. Throw some rabbets in the bottom of the slats to help the t-slot from pulling out. Pretty snazzy looking wasteboard if you ask me.
With all that being said, I have yet to use either the threaded inserts or the t-slot, so it was really just a huge waste of time. Looks cool though.